Neuronal voltage-gated calcium channels (VGCCs) serve complex yet essential physiological functions via their pivotal role in translating electrical signals into intracellular calcium elevations and associated downstream signalling pathways. There are a number of regulatory mechanisms to ensure a dynamic control of the number of channels embedded in the plasma membrane, whereas alteration of the surface expression of VGCCs has been linked to various disease conditions. Here, we provide an overview of the mechanisms that control the trafficking of VGCCs to and from the plasma membrane, and discuss their implication in pathophysiological conditions and their potential as therapeutic targets.

Introduction

Within neurons, calcium ions (Ca2+) are essential for regulating a myriad of cellular processes and ultimately physiological functions [1]. Like other cells, neurons use both extracellular and intracellular sources of Ca2+, and much has been learned about the mechanisms and players responsible for mobilizing Ca2+ [2]. Voltage-gated calcium channels (VGCCs) are essential for the initiation of the Ca2+ signalling cascades that are triggered by membrane depolarizations. They play a pivotal role in translating surface electrical signals into Ca2+ influx and intracellular Ca2+ elevations. These in turn support a number of cellular mechanisms ranging from synaptic integration to Ca2+-evoked gene transcription and neurotransmitter release [3,4]. VGCCs are pore-forming macromolecular complexes embedded in the plasma membrane of all kind of nerve cells. To date, ten genes encode for the pore-forming Cavα1 subunit of mammalian VGCCs and fall into two subfamilies: seven genes encode the high-voltage-activated (HVA) channels and consist of L-type (Cav1.1 to Cav1.4), P/Q-type (Cav2.1), N-type (Cav2.2), R-type (Cav2.3) and three genes encode the low-voltage-activated (LVA) channels represented exclusively by T-type channels (Cav3.1 to Cav3.3) (Figure 1) [46]. Cavα1 consists of four homologous membrane domains, each of them containing six transmembrane helices (S1–S6) and an extracellular re-entrant loop (so-called P-loop) responsible for shaping the pore and the selectivity filter of the Ca2+ channel. The four membrane domains are connected via variable cytoplasmic (loops I-II, II-III, III-IV) and N- and C-terminal regions that form molecular hubs for binding of regulatory proteins and post-translational modification of the channel. In addition to the Cav-pore forming subunit, HVA channel complexes contain a number of ancillary subunits, namely β, α2δ, and in some circumstances γ [4]. Initially identified with the skeletal dihydropyridine receptor complex [7], they are widely expressed in the nervous system where they associated with most of the HVA channel isoforms and are essential for cell surface expression and functioning of the channel [8]. In contrast, these ancillary subunits have little, if any, influence on the expression and function of T-type channels [911].

Molecular composition and diversity of VGCCs

Figure 1
Molecular composition and diversity of VGCCs

(A) Membrane topology of the Cavα1-pore forming subunit. It consists of four repeats (domain I to IV) made out of six transmembrane segments (S1 to S6) and connected by cytosolic regions (linker I-II to III-IV). The arginine-rich S4 segments of each of the four domains form the voltage sensor, whereas the pore forming loops connecting segments S5 and S6 comprise the Ca2+ selectivity elements of the channel. (B) Schematic representation of the VGCC complex, consisting of the Cav-pore forming subunit surrounded by β (yellow), α2δ (green) and γ (brown) ancillary subunits. (C) Diversity of VGCCs. The HVA subfamily is composed of Cav1.x (L-type) and Cav2.x (P/Q-, N- and R-type) channels, whereas Cav3.x channels (T-type) form the LVA subfamily.

Figure 1
Molecular composition and diversity of VGCCs

(A) Membrane topology of the Cavα1-pore forming subunit. It consists of four repeats (domain I to IV) made out of six transmembrane segments (S1 to S6) and connected by cytosolic regions (linker I-II to III-IV). The arginine-rich S4 segments of each of the four domains form the voltage sensor, whereas the pore forming loops connecting segments S5 and S6 comprise the Ca2+ selectivity elements of the channel. (B) Schematic representation of the VGCC complex, consisting of the Cav-pore forming subunit surrounded by β (yellow), α2δ (green) and γ (brown) ancillary subunits. (C) Diversity of VGCCs. The HVA subfamily is composed of Cav1.x (L-type) and Cav2.x (P/Q-, N- and R-type) channels, whereas Cav3.x channels (T-type) form the LVA subfamily.

A number of regulatory mechanisms act on VGCCs to indirectly regulate the amplitude, duration and subcellular localization of the Ca2+ signal. Indeed, control of VGCCs occurs at many different levels, starting with the control of channel subunits at the mRNA level. The modulation of VGCCs by RNA editing and alternative pre-mRNA splicing has been previously reviewed [12] and is considered a very important mechanism for diversifying calcium signalling. In addition, much attention has focused on the mechanisms that regulate the gating of the channel at the cell surface, including but are not limited to the modulation by synaptic proteins [13]; channel dimerization with other ion channels and receptors [14]; and the activation of G-protein-coupled receptors and downstream signalling pathways including phosphorylation [15]. Control of VGCCs may also occur at the level of the channel subunit trafficking to and from the plasma membrane [16]. Although the mechanisms controlling the expression of VGCCs along with those controlling their subcellular targeting are by far the least understood, a number of recent studies have uncovered essential factors and signalling pathways to ensure an optimal density of channels in the plasma membrane. In this review, we consider mechanisms that control the trafficking of VGCCs. We review the role of channel ancillary subunits and other interacting proteins in the expression of the channel. We also consider the importance of post-translational modifications including glycosylation and ubiquitination in the trafficking and stability of the channel at the cell surface. Finally, we discuss the implication of these regulatory mechanisms in chronic disorders of VGCCs, and analyse their potential as therapeutic targets.

Ancillary subunit-dependent trafficking of VGCCs

β-subunit

The β-subunit of VGCCs is a 55-kDa cytosolic protein that belongs to the membrane-associated guanylate kinase (GK) family. It consists of SH3 and GK domains that are highly conserved among the different β isoforms (β1 to β4), and linked by a variable HOOK region [1719]. The β-subunit binds with high affinity (in vitro Kd of approximately 5 nM) to a conserved motif (QQ-E–L-GY–WI–E) so called alpha-interaction domain (AID) within the cytoplasmic linker between repeats I and II of the Cavα1 subunits of HVA channels [20]. In addition, crystal structures of different AID–β-core complexes have defined the counterpart biding region within the β-subunit called AID-binding pocket (ABP) formed by a hydrophobic groove in the GK domain [2123]. The first evidence for a role of the β-subunit in the expression of VGCCs arose from co-expression studies in Xenopus oocytes and mammalian cells where a spectrum of effects were observed including an increase in the current amplitude by orders of magnitude [2426]. In addition, knockdown of β-subunits in dorsal root ganglion (DRG) neurons using a pan oligonucleotide antisense against all β-subunit isoforms resulted in a significant, albeit incomplete, decrease in the calcium current [27]. It is interesting to note that in contrast with the effects that have been reported in heterologous expression systems, Cav1.2 current densities in cardiomyocytes lacking the Cavβ2 subunit show only a moderate reduction in Cav1.2 channel expression levels [28]. There appeared to be no compensation from other Cavβ-subunit isoforms, but it is possible that other compensatory mechanisms that increase Cav1.2 channel trafficking may have been activated.

Although β-subunit-dependent potentiation of the Ca2+ current is multifactorial and clearly includes an increase in the opening probability of the channel [2933], a role in the trafficking of the channel to the cell surface rapidly emerged as the key function of these subunits. Based on the observation that a CD8 fusion construct of the I-II linker of Cav2.1 is retained in the endoplasmic reticulum (ER) unless co-expressed with a β-subunit prompted, it was proposed that the β-subunit may shield an ER retention signal in the I-II linker of the Cavα1 subunit, thus enhancing the exit of the channel from the ER [34]. However, this hypothesis was later challenged by a number of additional studies. First, an ER retention signal was never identified in the AID and surrounding regions, and deletion of the AID domain in Cav2.1 failed to mimic the effect of the β-subunit in terms of surface expression of the channel [17]. Second, the I-II linkers from various Cavα1 isoforms, despite all containing the AID motif, do not cause ER retention of CD8 or CD4 fusion proteins [35,36]. Third, substitution of the I-II linker of the LVA Cav3.1 channel (which does not require the presence of a β-subunit to translocate to the cell surface) with the domain I-II linker of different HVA channels including Cav1.2, Cav2.1 and Cav2.2 did not produce ER retention of the T-type channel but in contrast caused an up-regulation of the current [37,38]. In order to re-evaluate the mechanisms of β-mediated up-regulation of HVA channels, all of the T-type Cav3.1 channel intracellular linkers were systematically swapped with corresponding regions of the Cav1.2 channel, individually or in combination, and surface expression of the chimaeric channel was examined in the presence or absence of a β-subunit [38]. This elegant study suggested that the I-II linker of Cav1.2 in fact contains an ER ‘export’ signal, whereas all the other intracellular regions were found to contain some elements of ER retention signals. In an attempt to reconcile these divergent results, it was proposed that binding of the β-subunit to the I-II loop of the Cavα1 subunit may restructure the intramolecular arrangement of the intracellular linkers, favouring the ‘export’ conformation over the retention signal (Figure 2) [38]. A number of additional studies also reported a cross-talk between β-subunit and proteasome-dependent degradation of the channel. This aspect is further discussed in the section concerning the control of VGCC expression by the ubiquitin proteasome system.

Control of Cav1.2 channel trafficking by β-subunits

Figure 2
Control of Cav1.2 channel trafficking by β-subunits

The Cav1.2 channel contains an ER ‘export’ signal (green) located in the I-II linker, and an ER retention signal (red) made of various molecular determinants located within the II-III and III-IV linkers and the N- and C-terminal regions of the channel, which possibly interact with a yet unknown ER resident protein. In the absence of β-subunit, the retention signal is stronger than the ‘export’ signal and the channel is retained in the ER. Binding of a β-subunit on to the I-II linker triggers a molecular reorganization of the intracellular regions of the channel that diminishes the strength of the retention signal relative to the ‘export’ signal, leading to the exit of the channel from the ER and its trafficking to the cell surface.

Figure 2
Control of Cav1.2 channel trafficking by β-subunits

The Cav1.2 channel contains an ER ‘export’ signal (green) located in the I-II linker, and an ER retention signal (red) made of various molecular determinants located within the II-III and III-IV linkers and the N- and C-terminal regions of the channel, which possibly interact with a yet unknown ER resident protein. In the absence of β-subunit, the retention signal is stronger than the ‘export’ signal and the channel is retained in the ER. Binding of a β-subunit on to the I-II linker triggers a molecular reorganization of the intracellular regions of the channel that diminishes the strength of the retention signal relative to the ‘export’ signal, leading to the exit of the channel from the ER and its trafficking to the cell surface.

Altogether, these findings indicate that the β-subunit plays an essential role in the expression of HVA channels at the cell surface by stimulating the exit of the channel from the ER, and also by diverting the channel from the proteasomal degradation pathway. Whether these two mechanisms are independent or linked with each other needs to be further analysed. On the other hand, it is likely that a pool of channels may remain stagnant in the ER, protected from degradation, and awaiting for a trigger signal to translocate to the cell surface to rapidly support cell adaptation to various stimuli or environmental cellular conditions.

α2δ subunit

The α2δ subunit is an extracellular component of the channel complex, which is essential for cell surface trafficking, functional expression and pharmacological modulation of the Cav-pore forming subunit [3941]. Each of the four α2δ isoforms (α2δ-1 to α2δ-4) is transcribed and translated from a single gene, and undergoes a number of post-translational modifications that have important consequences on the fate and behaviour of the protein. First, proteolytic cleavage generates α2 and δ peptides that remain associated by disulfide bonds. Second, a glycosylphosphatidylinositol (GPI) moiety is attached to the C-terminal region of the δ peptide, and contributes to the anchoring of the protein to the plasma membrane after it has been secreted [42]. Third, α2δ is heavily glycosylated, which accounts for approximately a third of its total molecular weight [43]. The role of glycosylation of α2δ in the trafficking of HVA channels is discussed later in this review. All α2δ subunits contain a Von Willebrand factor A (VWF-A or VWA) domain, which represents a dinucleotide binding fold with a metal ion adhesion (MIDAS) motif and participates in a number of divalent cation interactions [44]. This subunit also contains two bacterial chemosensory-like domains (Cache) located downstream of the VWA domain [45]. The α2δ subunits are present in both skeletal [7], cardiac [46] and neuronal channel complexes [47,48], and it is likely that all HVA channels can associate with α2δ. Similar to what has been shown with the β-subunit, α2δ subunits increase surface expression of various Cavα1 isoforms including Cav1.2 [31,4951], Cav2.1 [5155], Cav2.2 [50,51,54,56], both in co-expression studies and native conditions. In contrast, α2δ seems to be less essential for the expression of Cav2.3 at the cell surface [30,57]. In addition to the effects of this subunit on channel trafficking, an increased opening probability of the channel in the presence of α2δ has been reported [29], and proteolytic cleavage of α2δ is essential for voltage-dependent activation of the channel at the cell surface [58]. Moreover, decreased internalization of the channels from the cell surface in the presence of α2δ subunits has been reported [59].

The exact mechanism by which α2δ potentiates surface expression of HVA channels is still up for debate. It was reported that the MIDAS motif in the VWA domain of α2δ-1 and α2δ-2 is critical to mediate this process [54,60]. Considering that the VWA domain is involved in protein–protein interactions, it is a possibility that α2δ may interact with proteins involved in the trafficking of the channel, or directly with the Cav subunit to promote the trafficking of the channel complex. Consistent with this notion, the recent structure of the skeletal muscle Cav1.1 channel complex determined by single-particle cryo-EM shed light on the molecular determinants involved in α2δ/Cavα1 interactions [61]. Consistent with previous biochemical studies [62], α2δ interacts with the extracellular loops of repeats I to III of the Cavα1 subunit via its VWA and Cache1 domains. In addition, there is pharmacological evidence for a role of α2δ/Cavα1 interaction in the trafficking of the channel. For instance, the antiepileptic/antiallodynic drugs gabapentin and pregabalin [6365] target α2δ [66,67]. Although the exact binding determinants of gabapentinoid drugs have not all been identified yet, a number of amino acids, especially the third arginine (R) in the RRR motif located upstream the VWA domain, were shown to contribute to the binding [68,69]. Interestingly, gabapentin was found to not only preclude the trafficking of Cav2.1 and Cav2.2 channels to the cell surface [56], but also counteract the increased expression of Cav2.2 channels associated with chronic pain conditions [70]. In addition, gabapentin inhibits rab11-dependent recycling of α2δ-2 from post-Golgi compartments to the cell surface, which may in turn reduce cell surface expression of the channel complex [71]. Interestingly, the mutation of the third arginine in the RRR motif to an alanine (RRA) that alters the binding of gabapentin was shown to abolish the ability of α2δ to enhance surface expression of the channel [56,72], suggesting that α2δ-dependent expression of the channel relies on the coupling with the Cavα1 subunit, and that gabapentinoid drugs exert their effect by disrupting the Cavα12δ complex.

Altogether, it is unambiguous that α2δ is essential for the trafficking and surface expression of HVA channels. However, it is also apparent that the exact mechanisms by which α2δ potentiates the trafficking of the channel remain elusive. Although a biochemical interaction between α2δ and the Cavα1 subunit seems to be required, it is still elusive the way Cavα12δ complex traffics to the cell surface and whether ER retention signals are involved in this regulation.

γ-subunit

The γ-subunit is a 33-kDa transmembrane protein initially described as a component of the skeletal muscle channel complex [7], and it was later demonstrated that nerve cells also express various homologues of the γ-subunit. To date, eight isoforms have been documented (γ1 to γ8), but compared with β and α2δ subunits, little attention has been focused on the γ-subunit, probably because of its relative mild effect on the channel function when expressed in Xenopus oocytes or mammalian cells [7378]. However, evidence exists for a role of γ in the modulation of native channels. For instance, the role of γ2, also known as stargazin [79], in the modulation of ion channels is best exemplified by its implication in absence seizures in the stargazer mouse that carries a transposon insertion in the gene encoding for γ2 [79]. This insertion severely reduces the expression of the γ2 subunit [8082], and is accompanied by an increased current density of both HVA and LVA channels in thalamocortical relay nuclei [83]. However, in vitro studies tend to suggest a direct modulation of the channel activity rather than an altered trafficking of the channel per se. Indeed, reduced Cav2.2 current density in cells co-expressing γ7 is not accompanied by a reduction in the surface expression of the channel protein [84]. Similarly, Cav3.1 T-type currents are inhibited in an atrial cell line expressing γ6 but this effect does not appear to be mediated by reduced channel trafficking [8587]. In contrast, altered trafficking of AMPA receptors from the Golgi apparatus to the plasma membrane was documented in the stargazer mouse, indicating that γ2 is essential for surface expression and postsynaptic targeting of the receptor [88,89]. Interestingly, the γ4 isoform that shares a high degree of amino acid conservation with γ2 was found to be even more effective in trafficking AMPA receptors to the cell surface [90]. Indeed, neuronal γ subunits may not have a primary role as bona fide calcium channel subunits, but are instead rather known to be important constituents of AMPA and kainate receptors. Along these lines, γ7 has been shown to exhibit binding to mRNA [91], and it is possible that the effects of co-expression of these subunits with various calcium channel isoforms are more diffusely related to changes in gene expression of channels or their regulatory elements, which in turn may account for altered ion channel trafficking or gating. This may fit with the observation that the related γ2 subunit regulates N-type channels indirectly via a G-protein dependent pathway [92].

Trafficking regulation of VGCCs by other interacting proteins

Calmodulin

Calmodulin (CaM) is a multifunctional intermediate Ca2+-binding protein essential for neuronal signalling [93]. The fact that CaM associates with virtually all HVA channels has led the proposal that this protein might be considered as an integral component of the Ca2+ channel complex per se [93], and prompted some authors to propose the term ‘calmodulation’ to cover any kind of CaM-dependent regulation of ion channels. The multifaceted regulation of VGCCs by CaM has extensively been reviewed over the past 2 years [9496]. In this section, we focus exclusively on its specific role in the trafficking of the channel complex. Although a number of domains located in the C-terminal region of the Cavα1 subunit of HVA channels have been shown to be involved in the binding of Ca2+/CaM with the channel, the IQ domain has emerged as prerequisite for the binding of Ca2+ free Apo-CaM. Although the role of CaM in the modulation of channel activity has been extensively documented, its role in the trafficking of the channel has remained controversial. Initial data suggested that CaM has no effect on the surface expression of Cav1.2 in HEK-293 cells, either in the presence or absence of the ancillary subunits β and α2δ [97]. In contrast, surface expression of Cav1.2 channels lacking the PreIQ3 region located upstream of the IQ domain and important for the binding of Ca2+/CaM is completely abolished despite the presence of the β2a subunit [98]. Consistent with a role of CaM in the expression of VGCCs, trafficking of Cav1.2 channels to distal dendrites of hippocampal neurons is accelerated by Ca2+/CaM but not by Apo-CaM [99]. In addition, a number of studies have reported that mutations in the EF-hand domain of Cav1.2 channels alter current amplitude [100102]. Although these mutations certainly altered the gating modulation of the channel [99,103], it is also a possibility that CaM-dependent trafficking of the channel was hampered. In addition to the CaM-binding domains in the C-terminal region of the channel, the N-terminal region of Cav1.2 contains two additional biding regions that are not present in Cav2.x channels [104106]. However, there is no obvious evidence for a role in the trafficking of the channel. Recently, a CaM kinase II-biding site was identified in the N-terminal region of Cav1.2 important for cell surface expression of the channel [107]. Interestingly, disruption of the CaMKII-binding site caused a significant reduction in the expression of the channel protein at the cell surface when expressed in tsA-201 cells. Whether a cross-talk exists between the binding of Ca2+/CaM and CaMKII remains to be analysed.

We note that many studies that investigate the role of CaM and/or CamKII interactions rely on point mutations in the critical binding domains on the channel. In interpreting the functional data obtained with mutant constructs, it is thus important to consider the possibility that mutations may have more global effects on channel folding and trafficking per se. Nonetheless, these data shed light on a potential role for Ca2+/CaM in regulating cell surface expression of VGCCs, even though the underlying mechanisms supporting this regulation remain to be precisely elucidated.

Stac adaptor proteins

Stac adaptor proteins form a family of SH3 and cysteine-rich domain-containing proteins whose primary functions have remained largely unknown [108]. Although Stac3 is essentially expressed in skeletal muscle, Stac1 and Stac2 are widely expressed in the peripheral and central nervous system [109]. Initial studies reported an essential role for Stac3 in the assembly and functioning of the excitation–contraction coupling machinery and maturation of skeletal muscle [110113]. A role for Stac3 in the trafficking of Cav1.1 channels to the cell surface was then documented in tsA-201 cells [114,115]. These results prompted us to analyse whether Stac proteins may also contribute to the expression of neuronal VGCCs, especially T-type channels. As already mentioned, surface expression of LVA channels is barely influenced by the usual channel ancillary subunits, and although the I-II loop was reported to contribute to the expression of the channel [116,117], little is known about the molecular mechanisms controlling the trafficking of T-type channels. Our laboratory has shown that Stac1 binds to the distal region of the N-terminus of Cav3.2 channels and potentiates T-type currents in tsA-201 cells [118]. Although the main gating properties of the channel were not affected by Stac1, surface expression of Cav3.2 was increased suggesting that the enhanced T-type conductance was essentially caused by an increased expression of the channel at the plasma membrane. Whether Stac1 potentiates the trafficking of Cav3.2 to the cell surface or stabilizes the channel in the plasma membrane remains to be analysed [119].

Altogether, Stac proteins are emerging as important modulators of T-type channel trafficking, and likely have a broader implication in the expression of VGCCs in general.

Kelch-like 1

Kelch-like 1 (KLHL1) belongs to a family of actin-organizing proteins that interacts with actin and is mostly expressed in neuronal tissues. The Ca2+ conductance in tsA-201 cells expressing Cav2.1, Cav3.1 and Cav3.2 was found increased upon co-expression of KLHL1 [120,121]. This was further analysed for Cav3.1 and Cav3.2 channels and shown to be due to increased surface expression of the channel proteins. Biochemical studies also indicated that KLHL1 can be immunoprecipitated with the channels, but the detailed molecular determinants of the interaction have not been characterized. In addition, although pharmacological disruption of actin filaments did not affect the activity of T-type channels per se, it did eliminate KLHL1-dependent potentiation of the channels [120]. Similar observations were made upon disruption of endosomal recycling suggesting that KLHL1 enhances surface expression of T-type channels by potentiating their re-insertion into the plasma membrane from recycling endosomes (Figure 3) [120]. The role of KLHL1 in the expression of VGCCs in further supported by the observation that shRNA knockdown of KLHL1 in hippocampal neurons in culture caused a dramatic decrease in both HVA and LVA Ca2+ currents [122]. These results are consistent with the observation that Cav2.1 and Cav3.2 are down-regulated in hippocampal neurons from KLHL1 KO mice [123]. However, concomitant up-regulation of Cav1.2 and Cav3.1 was also observed in KLHL1 KO hippocampal neurons, possibly reflecting the occurrence of a compensatory process. Nevertheless and consistent with the presynaptic role of Cav2.1 and Cav3.2, the synaptic activity of KLHL1 KO neurons remained compromised [123].

KLHL1-dependent trafficking of T-type channels

Figure 3
KLHL1-dependent trafficking of T-type channels

The steady-state expression of T-type channels at the cell surface results from the number of channels coming to and getting internalized from the plasma membrane. Although T-type channels are internalized and degraded, expression of the actin-binding protein KLHL1 allows the recycling and re-insertion of the channels into the plasma membrane.

Figure 3
KLHL1-dependent trafficking of T-type channels

The steady-state expression of T-type channels at the cell surface results from the number of channels coming to and getting internalized from the plasma membrane. Although T-type channels are internalized and degraded, expression of the actin-binding protein KLHL1 allows the recycling and re-insertion of the channels into the plasma membrane.

Overall, these results emphasize the contribution of KLHL1 and actin-binding proteins in the expression of Ca2+ channels at the cell surface, and it remains to be determined if this regulation involves some of the channel molecular determinants previously identified in the trafficking of the channel.

Role of post-translational modifications in VGCC trafficking

Ubiquitination and the ubiquitin proteasome system

Ubiquitin-dependent degradation of VGCCs by the ubiquitin-proteasome system (UPS) has emerged as an important means to control the number of channels expressed at the cell surface [124]. Ubiquitination of proteins relies on the attachment of an ubiquitin moiety by an ubiquitin ligase, and dictates the fate of the target protein [125]. Although monoubiquitination generally triggers the internalization of the protein that is either further degraded in lysosomes or recycled back into the plasma membrane, polyubiquitinated proteins are targeted to the proteasome system for proteolysis. Although ubiquitination is a universal mechanism to control the fate of proteins, ubiquitination of VGCCs was only recently documented. For instance, it was proposed that Cav1.2 channels are ubiquitinated by the ubiquitin ligase RFP2, and that ubiquitinated channels interact with key proteins of the endoplasmic reticulum-associated protein degradation (ERAD) complex including derlin-1 and p97, which in turn triggers the targeting of the channel to the proteasome system (Figure 4) [36]. Consistent with this notion, the Ca2+ current density and surface expression of Cav1.2 channels was found significantly increased in cells expressing a dominant negative RFP2 construct [36]. In addition, it was demonstrated that the β-subunit prevents RFP2-mediated ubiquitination of Cav1.2, diverting the channel away from its degradation by the proteasome system [36]. This aspect is further supported by the observation that surface expression of the channel in the absence of β-subunit is partially rescued by the proteasome inhibitor MG132. Additional reports indicated that ubiquitination of Cav1.2 channels may also happen via the ubiquitin ligase Nedd4-1 [126], and counteracted by the ubiquitin-specific protease (USP)2-45 [127]. However, despite the fact that USP2-45 can indeed deubiquitinate the channel, Ca2+ currents in tsA-201 cells expressing Cav1.2 with USP2-45 were dramatically reduced, suggesting a more complex regulatory mechanism [127]. The ubiquitination of Cav2.2 channels has also been reported, a process that is modulated by the β-subunit as part of its protective function [128,129]. Furthermore, Cav2.2 was shown to interact with a macromolecular complex containing the light chain 1 subunit (LC1) of the microtubule-associated protein 1B (MAP1B) and the ubiquitin conjugase UBE2L3 to control surface expression of the channel [130,131]. Proteasome-dependent degradation of Cav2.2 channels is also enhanced by the binding of the fragile X mental retardation protein (FMRP) with the channel, a process that is defective in fragile X syndrome [132]. In addition, a role for alternative splicing of the pre-mRNA in the modulation of ubiquitin-dependent degradation of the channel has emerged. For instance, the Cav2.2 channels containing exon 37b have increased ubiquitination levels compared with channels containing exon 37a, which is correlated with a reduced expression of the channel [133]. Considering that cell-specific alternative splicing of exon 37a exists in nociceptors, decreased ubiquitination of Cav2.2 e37a may have important consequences in pain processing. This effect might be even amplified by the fact that the adaptor protein complex-1 (AP-1) potentiates the trafficking of Cav2.2 e37a channels from the trans-Golgi to the cell surface, but not of the e37b variant that does not contain the AP-1 binding motif [132]. Along these lines, it was established that ubiquitination of Cav3.2 T-type channels is an important mechanism for regulating pain signalling in primary afferent nociceptive neurons. For instance, Cav3.2 channels are ubiquitinated within the III-IV linker of the channel by the ubiquitin ligase WWP1, whereas ubiquitin moieties can be removed by the ubiquitin protease USP5, hence controlling the ubiquitination/deubiquitination levels of the channel and its expression at the cell surface (Figure 5) [134]. In addition and consistent with the essential role of Cav3.2 channels in pain signalling, in vivo knockdown of USP5 mediated analgesia in both inflammatory and neuropathic mouse models of mechanical hypersensitivity [134]. Importantly, analgesia was reproduced by in vivo disruption of Cav3.2/USP5 interaction using interfering peptides or small organic molecules, revealing the potential therapeutic interest of targeting ubiquitination signalling as a new analgesic avenue [135,136].

Control of Cav1.2 channel expression by the UPS

Figure 4
Control of Cav1.2 channel expression by the UPS

Ubiquitination (red chain) of Cav1.2 by the ubiquitin ligase RFP2 triggers the association of the channel with ERAD proteins Derlin1 and P97, leading to the degradation of the channel complex by the proteasome system. In the presence of a β-subunit, Cav1.2 is protected from RFP2-dependent ubiquitination, allowing the trafficking of the channel to the cell surface.

Figure 4
Control of Cav1.2 channel expression by the UPS

Ubiquitination (red chain) of Cav1.2 by the ubiquitin ligase RFP2 triggers the association of the channel with ERAD proteins Derlin1 and P97, leading to the degradation of the channel complex by the proteasome system. In the presence of a β-subunit, Cav1.2 is protected from RFP2-dependent ubiquitination, allowing the trafficking of the channel to the cell surface.

A dynamic ubiquitination/deubiquitination balance controls expression of Cav3.2 channels at the cell surface

Figure 5
A dynamic ubiquitination/deubiquitination balance controls expression of Cav3.2 channels at the cell surface

Although ubiquitination of Cav3.2 by the ubiquitin ligase WWP1 triggers the internalization and degradation of the channel, removal of ubiquitin moieties from the channel protein by the deubiquitinase USP5 increases the stability of the channel in the plasma membrane, leading to enhanced channel surface density.

Figure 5
A dynamic ubiquitination/deubiquitination balance controls expression of Cav3.2 channels at the cell surface

Although ubiquitination of Cav3.2 by the ubiquitin ligase WWP1 triggers the internalization and degradation of the channel, removal of ubiquitin moieties from the channel protein by the deubiquitinase USP5 increases the stability of the channel in the plasma membrane, leading to enhanced channel surface density.

Altogether, these data strongly support an important role of the UPS in the control of VGCCs expression. Although most attention has focused on the pore-forming Cavα1 subunit, it is likely that ancillary subunits also undergo ubiquitination, which may provide an additional level of control over the expression of the Ca2+ channel complex.

Asparagine-linked glycosylation

Asparagine (N)-linked glycosylation represents another post-translational modification recognized as essential for the expression and modulation of ion channels in general and VGCCs particularly [137]. N-glycosylation consists of the orchestrated enzymatic conjugation of an oligosaccharide tree (glycan) to an asparagine (N) residue in a consensus motif N-X-S/T (X being any residue although the nature of this residue strongly influences the probability of glycosylation) within the target protein. Although much attention has focused on the role of N-glycosylation in the folding and ER quality control of nascent proteins, the importance of N-glycosylation in the trafficking and stability of the channel at the plasma membrane has emerged. All of the ten pore-forming Cavα1 subunits are glycosylated, and pharmacological or molecular disruption of canonical glycosylation sites has shed light on the importance of the glycan tree in the trafficking of the channel. For instance, disruption of the glycosylation of Cav1.2 expressed in Xenopus oocytes caused a substantial decrease in the surface expression and Ca2+ conductance [138]. Biochemical evidence for glycosylation of the skeletal channel homologue Cav1.1 is also available but no functional data have yet been reported [139].

The most extensive characterization to date concerns T-type channels. The initial evidence for the glycosylation of T-type channels arose from biochemical studies of Cav3.1 and Cav3.3 channels. Although the apparent molecular weight of Cav3.1 and Cav3.3 varies with respect to their regional brain expression and also during neuronal development [140], enzymatic deglycosylation of the channels with PNGase F was sufficient to abolish these differences, suggesting that Cav3.1 and Cav3.3 do undergo glycosylation, but also that their degree of glycosylation differs with respect to their regional and developmental expression pattern [141]. However, it was only recently that the functional role of N-glycosylation in the trafficking of T-type channels was analysed. We and others have shown that glycosylation of Cav3.2 channels at specific loci is essential for surface expression of the channel protein [142,143]. For instance, disruption of the glycosylation loci at asparagine N192 and N1466 in the human Cav3.2 channel caused a significant reduction in the surface density of the channel that was not accompanied by a reduction in the total expression level of the channel, suggesting a role for N-glycosylation in the trafficking of the channel. Furthermore, analysis of the dynamics of the channels in the plasma membrane revealed that decreased surface expression of Cav3.2 was largely caused by the enhanced internalization of glycosylation-deficient channels (Figure 6) [144]. In addition, we have reported that enhanced Cav3.2 surface expression during chronic elevation of external glucose levels depends on the glycosylation of the channel [142,144]. This aspect may have important implications in chronic disorders such as peripheral painful diabetic neuropathy where enhanced expression of T-type channels is believed to contribute to the development and maintenance of this condition [145148]. This notion is further supported by the observation that peripheral injection of neuraminidase in an animal model of diabetes reversed neuropathic pain [143]. Altogether, these data indicate that N-glycosylation of Cav3.2 channels, in addition to influencing the gating properties of the channel [149], contributes to the maintenance of the channel protein in the plasma membrane, and may have important physiopathological implications.

Glycosylation modulates surface expression of Cav3.2 channels

Figure 6
Glycosylation modulates surface expression of Cav3.2 channels

Although N-glycosylation of Cav3.2, especially at asparagine residues N192 and N1466 (in the human channel), has little influence on the forward trafficking to the cell surface, it enhances the life-time of the channel in the plasma membrane by slowing down its internalization. In addition, N-glycosylation supports glucose-dependent potentiation of the trafficking of Cav3.2 channels to the cell surface.

Figure 6
Glycosylation modulates surface expression of Cav3.2 channels

Although N-glycosylation of Cav3.2, especially at asparagine residues N192 and N1466 (in the human channel), has little influence on the forward trafficking to the cell surface, it enhances the life-time of the channel in the plasma membrane by slowing down its internalization. In addition, N-glycosylation supports glucose-dependent potentiation of the trafficking of Cav3.2 channels to the cell surface.

In addition to the Cavα1 subunit, glycosylation has been reported for α2δ and γ ancillary subunits [7]. As previously mentioned, the α domain of α2δ subunit is extensively glycosylated and initial reports suggested that N-glycosylation might stabilize its interaction with the channel [150]. In addition, it was proposed that glycosylation of α2δ is essential for supporting α2δ-dependent expression of Cav1.3 and Cav2.2 channels [151,152]. Recently, sequential disruption of a number of glycosylation sites in the α2δ-1 subunit, followed by examination of its surface expression, has uncovered a number of glycosylation loci that are essential for the expression of α2δ-1 at the cell surface [153]. However, it is not clear whether these effects are caused by a decreased trafficking of α2δ to the cell surface or a reduced stability of the protein in the plasma membrane. Consistent with the chaperone role of α2δ, Ca2+ currents in HEK-293 cells expressing Cav1.2 channels were found reduced in the presence of glycosylation-deficient α2δ-1. It was, however, not established if this effect relied on the trafficking of the channel complex to the cell surface or instead involved the direct modulation of the channel activity. Indeed, a number of other glycosylation sites including asparagine N136 and N184 that initially were found essential for functional expression of Cav2.2 channels [151], had little influence on the expression of α2δ-1 at the plasma membrane [153]. Interestingly, these glycosylation loci are located within the VWA-N region and may contribute to the functional interaction of α2δ-1 with the channel. This notion is supported by the observation that disruption of a glycosylation locus located in the VWA domain (N348) altered expression of Cav1.2 channels [153]. Although a counterpart analysis of the surface expression of the Cavα1 subunit in the presence of glycosylation-deficient α2δ-1 would be required to uncover the exact mechanisms by which glycosylation of α2δ influences expression of the channel, these data clearly indicate that N-glycosylation is an important factor contributing to surface expression of α2δ. It is worth noting that a number of glycosylation loci are located in the vicinity of the binding determinants of gabapentinoid drugs and may influence the pharmacology of the channel. Similar to α2δ, glycosylation of the γ-subunit seems to contribute to its expression at the plasma membrane, and disruption of the asparagine N48 located in the first extracellular loop connecting the first and second transmembrane segments disrupted the trafficking to the cell surface [154]. Interestingly, despite reduced surface expression of γ, Cav2.2 currents were still inhibited, questioning the functional mechanism by which γ modulates the functioning of the channel [155].

Mechanisms of subcellular targeting of VGCCs

Although the trafficking and dynamic of VGCCs at the plasma membrane are essential aspects, their specific targeting to subcellular loci is crucial for the maintenance of physiological regulation of normal neuronal activity. Although in some situations Ca2+ channels are widely distributed throughout the cell [156,157], they usually display a more restricted subcellular expression that allows them to fulfil specific functions. For instance, L-type channels are predominantly expressed in proximal dendrites where they are involved in dendritic Ca2+ signalling resulting from back-propagating action potentials and synaptic plasticity, and on cell bodies where they support activity-dependent modulation of gene transcription [158]. In contrast, N- and P/Q-type channels are primarily targeted to presynaptic terminals where they support voltage-dependent neurotransmitter release [159162]. However, the detailed molecular mechanisms underlying the subcellular localization of VGCCs are still a matter of active investigations. Interaction of VGCCs with the β-subunit seems to contribute to the subcellular localization of the channel complex. Interaction of Cav2.1 channels with the β4-subunit appears to contribute to the presynaptic targeting of the channel [163165]. However, the detailed mechanisms of β-mediated targeting of the channel remain unclear. Interaction of Cav2.1 and Cav2.2 channels with a number of presynaptic proteins was also found to be important for the targeting of the channels into nerve terminals. This targeting relies on the binding of some of the proteins of the vesicular release machinery (SNAREs) including syntaxin 1A, SNAP-25 and synaptotagmin to the synprint region within the cytosolic II-III linker of the channel [166168]. Consistent with this notion, Cav2.2 splice variants that lack most of the synprint region fail to cluster into presynaptic terminals, and in contrast present an axonal expression profile [167,169]. The C-terminus of Cav3.2 also contains a synprint-like region responsible for interaction with syntaxin 1A and SNAP-25 [170] and may contribute to the targeting of T-type channels to presynaptic terminals [171] where they may support activity-dependent low-threshold exocytosis [172,173]. Despite evidence for the role of channel/SNARE interactions in the targeting of the channels, transplanting the synprint region of Cav2.2 into Cav1.2 was not sufficient to trigger axonal expression or synaptic clustering of the chimaera channel, suggesting the involvement of other targeting mechanisms in the incorporation of Cav2 channels into nerve terminals [167]. Along these lines, the C-terminus of Cav2.2 contains a PDZ and SH3 binding motifs that are required for interaction with presynaptic adapter proteins Mint-1 and CASK, and contribute to but not essential for synaptic targeting of the channel [174,175].

The mechanisms responsible for somatodendritic targeting of L-type channels are less characterized but may involve interactions with structural proteins. For instance, Cav1.3 channels associate with the postsynaptic adaptor protein Shank via a motif in the C-terminus of the channel, and co-localize at postsynaptic sites in hippocampal neurons [176]. Cav1.3 channels are also found at presynaptic sites in sensory hair cells where they interact with Ribeye [177]. In photoreceptors, Cav1.4 channels co-localize with the presynaptic scaffolding protein bassoon at the ribbon synapse [178]. A role for the β-subunit in the localization of L-type channel was also documented. For instance, point mutations in the AID region of Cav1.2 that disrupt the interaction with the β-subunit abolished the dendritic clustering of the channel complex in hippocampal neurons [179]. Interestingly, although Cav1.2 channels are targeted to the soma and dendrites of mature neurons, they are abundantly expressed in the growth cone of developing nerve cells [156]. It is conceivable that this switch in the expression pattern of Cav1.2 switch might reflect the existence of a dynamic and reversible association of the channel with different β isoforms [180,181]. Consistent with this notion, a reshuffling of the molecular composition of the N-type channel complex during postnatal development was documented, from β1b > β3 >> β2 at P2 to β3 > β1b4 at P14 and the adult stage [182]. Dynamic associations of β-subunits with Cav1.1 channels also exist in skeletal muscles [183]. In addition, it was reported that assembly and disassembly of Cavα12δ-1a complex play an important modulatory role in the Ca2+ channel [184]. More recently, a polybasic plasma membrane binding motif consisting of a cluster of four arginine residues in the I-II linker of Cav1.2 channels was identified. This motif forms a straight α-helix with the positive charges facing and interacting with negatively charged phospholipids in the plasma membrane. Besides modulating the gating of the channel, this cluster was found to be important for stabilizing the channel at the cell surface and neutralization of the arginine residues resulted in a decreased expression of the channel in the plasma membrane [185]. Considering the phospholipid asymmetry of the plasma membrane and related lipid-translocating enzymes, it is possible that this polybasic motif in Cav1.2 contributes to the subcellular localization of the channel as was reported for the clustering of acetylcholine receptors [186].

Concluding remarks and perspectives

The trafficking of VGCCs to the plasma membrane, and ultimately into subcellular loci, is an important aspect of the dynamics of these channels. To achieve this diversity, nerve cells have access to an extensive machinery from which they can select and assemble unique signalling systems with spatial and temporal properties necessary to control particular functions. In this review, we have highlighted some of the elements of this machinery underlying the expression of VGCCs, and it is likely that a number of additional players have not yet been identified. Whether some degree of redundancy exists as means of safeguarding critical neurological functions, it is clear that these systems are not perfect and the modified signalling pathways often results in the alteration of the expression of the calcium channels and consequently the emergence of multiple neurological disorders. However, the insights gained from understanding the fundamental mechanisms controlling the expression of these channels have opened new avenues for therapeutic intervention. The management of neuropathic pain with gabapentinoid drugs is one remarkable example, and recent results have emerged showing promising evidence that specific targeting of the trafficking of the calcium channel complex can be exploited as the basis for therapeutic intervention. This approach contrasts with the conventional and often unsuccessful method in targeting the channel activity per se, and undoubtedly opens new avenues for future drug development for a wide range of neurological disorders liked to calcium channel dysfunction [187].

Competing interests

The authors declare that there are no competing interests associated with the manuscript.

Funding

This work was supported by the Czech Science Foundation [grant number 15-13556S]; the Czech Ministry of Education Youth and Sports [grant number 7AMB15FR015]; Institute of Organic Chemistry and Biochemistry; the Canadian Institutes of Health Research; the Natural Science and Engineering Research Council; and Canada Research Chair (to G.W.Z.).

Abbreviations

     
  • AID

    alpha-interaction domain

  •  
  • CaM

    calmodulin

  •  
  • DRG

    dorsal root ganglion

  •  
  • ER

    endoplasmic reticulum

  •  
  • ERAD

    endoplasmic reticulum-associated protein degradation

  •  
  • GK

    guanylate kinase

  •  
  • HEK

    human embryonic kidney

  •  
  • HVA

    high-voltage-activated

  •  
  • KLHL1

    Kelch-like 1

  •  
  • KO

    knockout

  •  
  • LVA

    low-voltage-activated

  •  
  • MIDAS

    metal ion adhesion

  •  
  • NSF

    N-ethylmaleimide-sensitive fusion protein

  •  
  • RRR

    triple arginine

  •  
  • SNAP

    soluble NSF attachment protein

  •  
  • SNARE

    SNAP receptor

  •  
  • UPS

    ubiquitin-proteasome system

  •  
  • USP

    ubiquitin-specific protease

  •  
  • VGCC

    voltage-gated calcium channel

  •  
  • VWA

    Von Willebrand factor A

References

References
1
Berridge
,
M.J.
(
1998
)
Neuronal calcium signaling
.
Neuron
21
,
13
26
2
Berridge
,
M.J.
,
Bootman
,
M.D.
,
Roderick
,
H.L.
(
2003
)
Calcium signalling: dynamics, homeostasis and remodelling
.
Nat. Rev. Mol. Cell Biol.
4
,
517
529
3
Catterall
,
W.A.
(
2011
)
Voltage-gated calcium channels
.
Cold Spring Harb. Perspect. Biol.
3
,
a003947
4
Zamponi
,
G.W.
,
Striessnig
,
J.
,
Koschak
,
A.
,
Dolphin
,
A.C.
(
2015
)
The physiology, pathology, and pharmacology of voltage-gated calcium channels and their future therapeutic potential
.
Pharmacol. Rev.
67
,
821
870
5
Ertel
,
E.A.
,
Campbell
,
K.P.
,
Harpold
,
M.M.
,
Hofmann
,
F.
,
Mori
,
Y.
,
Perez-Reyes
,
E.
et al.  (
2000
)
Nomenclature of voltage-gated calcium channels
.
Neuron
25
,
533
535
6
Simms
,
B.A.
,
Zamponi
,
G.W.
(
2014
)
Neuronal voltage-gated calcium channels: structure, function, and dysfunction
.
Neuron
82
,
24
45
7
Takahashi
,
M.
,
Seagar
,
M.J.
,
Jones
,
J.F.
,
Reber
,
B.F.
,
Catterall
,
W.A.
(
1987
)
Subunit structure of dihydropyridine-sensitive calcium channels from skeletal muscle
.
Proc. Natl. Acad. Sci. U.S.A.
84
,
5478
5482
8
Arikkath
,
J.
,
Campbell
,
K.P.
(
2003
)
Auxiliary subunits: essential components of the voltage-gated calcium channel complex
.
Curr. Opin. Neurobiol.
13
,
298
307
9
Leuranguer
,
V.
,
Bourinet
,
E.
,
Lory
,
P.
,
Nargeot
,
J.
(
1998
)
Antisense depletion of beta-subunits fails to affect T-type calcium channels properties in a neuroblastoma cell line
.
Neuropharmacology
37
,
701
708
10
Dubel
,
S.J.
,
Altier
,
C.
,
Chaumont
,
S.
,
Lory
,
P.
,
Bourinet
,
E.
,
Nargeot
,
J.
(
2004
)
Plasma membrane expression of T-type calcium channel alpha(1) subunits is modulated by high voltage-activated auxiliary subunits
.
J. Biol. Chem.
279
,
29263
29269
11
Bae
,
J.
,
Suh
,
E.J.
,
Lee
,
C.
(
2010
)
Interaction of T-type calcium channel Ca(V)3.3 with the β-subunit
.
Mol. Cells
30
,
185
191
12
Lipscombe
,
D.
,
Andrade
,
A.
,
Allen
,
S.E.
(
2013
)
Alternative splicing: functional diversity among voltage-gated calcium channels and behavioral consequences
.
Biochim. Biophys. Acta
1828
,
1522
1529
13
Weiss
,
N.
,
Zamponi
,
G.W.
(
2012
)
Regulation of voltage-gated calcium channels by synaptic proteins
.
Adv. Exp. Med. Biol.
740
,
759
775
14
Zamponi
,
G.W.
(
2015
)
Calcium channel signaling complexes with receptors and channels
.
Curr. Mol. Pharmacol.
8
,
8
11
15
Proft
,
J.
,
Weiss
,
N.
(
2015
)
G protein regulation of neuronal calcium channels: back to the future
.
Mol. Pharmacol.
87
,
890
906
16
Dai
,
S.
,
Hall
,
D.D.
,
Hell
,
J.W.
(
2009
)
Supramolecular assemblies and localized regulation of voltage-gated ion channels
.
Physiol. Rev.
89
,
411
452
17
Maltez
,
J.M.
,
Nunziato
,
D.A.
,
Kim
,
J.
,
Pitt
,
G.S.
(
2005
)
Essential Ca(V)beta modulatory properties are AID-independent
.
Nat. Struct. Mol. Biol.
12
,
372
377
18
McGee
,
A.W.
,
Nunziato
,
D.A.
,
Maltez
,
J.M.
,
Prehoda
,
K.E.
,
Pitt
,
G.S.
,
Bredt
,
D.S.
(
2004
)
Calcium channel function regulated by the SH3-GK module in beta subunits
.
Neuron
42
,
89
99
19
Buraei
,
Z.
,
Yang
,
J.
(
2010
)
The β subunit of voltage-gated Ca2+ channels
.
Physiol. Rev.
90
,
1461
1506
20
Pragnell
,
M.
,
De Waard
,
M.
,
Mori
,
Y.
,
Tanabe
,
T.
,
Snutch
,
T.P.
,
Campbell
,
K.P.
(
1994
)
Calcium channel beta-subunit binds to a conserved motif in the I-II cytoplasmic linker of the alpha 1-subunit
.
Nature
368
,
67
70
21
Chen
,
Y.H.
,
Li
,
M.H.
,
Zhang
,
Y.
,
He
,
L.L.
,
Yamada
,
Y.
,
Fitzmaurice
,
A.
et al.  (
2004
)
Structural basis of the alpha1-beta subunit interaction of voltage-gated Ca2+ channels
.
Nature
429
,
675
680
22
Opatowsky
,
Y.
,
Chen
,
C.C.
,
Campbell
,
K.P.
,
Hirsch
,
J.A.
(
2004
)
Structural analysis of the voltage-dependent calcium channel beta subunit functional core and its complex with the alpha 1 interaction domain
.
Neuron
42
,
387
399
23
Van Petegem
,
F.
,
Clark
,
K.A.
,
Chatelain
,
F.C.
,
Minor
,
D.L.
(
2004
)
Structure of a complex between a voltage-gated calcium channel beta-subunit and an alpha-subunit domain
.
Nature
429
,
671
675
24
Singer
,
D.
,
Biel
,
M.
,
Lotan
,
I.
,
Flockerzi
,
V.
,
Hofmann
,
F.
,
Dascal
,
N.
(
1991
)
The roles of the subunits in the function of the calcium channel
.
Science
253
,
1553
1557
25
Hullin
,
R.
,
Singer-Lahat
,
D.
,
Freichel
,
M.
,
Biel
,
M.
,
Dascal
,
N.
,
Hofmann
,
F.
et al.  (
1992
)
Calcium channel beta subunit heterogeneity: functional expression of cloned cDNA from heart, aorta and brain
.
EMBO J.
11
,
885
890
26
Stea
,
A.
,
Dubel
,
S.J.
,
Pragnell
,
M.
,
Leonard
,
J.P.
,
Campbell
,
K.P.
,
Snutch
,
T.P.
(
1993
)
A beta-subunit normalizes the electrophysiological properties of a cloned N-type Ca2+ channel alpha 1-subunit
.
Neuropharmacology
32
,
1103
1116
27
Berrow
,
N.S.
,
Campbell
,
V.
,
Fitzgerald
,
E.M.
,
Brickley
,
K.
,
Dolphin
,
A.C.
(
1995
)
Antisense depletion of beta-subunits modulates the biophysical and pharmacological properties of neuronal calcium channels
.
J. Physiol.
482
,
481
491
28
Meissner
,
M.
,
Weissgerber
,
P.
,
Londoño
,
J.E.
,
Prenen
,
J.
,
Link
,
S.
,
Ruppenthal
,
S.
et al.  (
2011
)
Moderate calcium channel dysfunction in adult mice with inducible cardiomyocyte-specific excision of the cacnb2 gene
.
J. Biol. Chem.
286
,
15875
15882
29
Wakamori
,
M.
,
Mikala
,
G.
,
Mori
,
Y.
(
1999
)
Auxiliary subunits operate as a molecular switch in determining gating behaviour of the unitary N-type Ca2+ channel current in Xenopus oocytes
.
J. Physiol.
517
,
659
672
30
Jones
,
L.P.
,
Wei
,
S.K.
,
Yue
,
D.T.
(
1998
)
Mechanism of auxiliary subunit modulation of neuronal alpha1E calcium channels
.
J. Gen. Physiol.
112
,
125
143
31
Shistik
,
E.
,
Ivanina
,
T.
,
Puri
,
T.
,
Hosey
,
M.
,
Dascal
,
N.
(
1995
)
Ca2+ current enhancement by alpha 2/delta and beta subunits in Xenopus oocytes: contribution of changes in channel gating and alpha 1 protein level
.
J. Physiol.
489
,
55
62
32
Luvisetto
,
S.
,
Fellin
,
T.
,
Spagnolo
,
M.
,
Hivert
,
B.
,
Brust
,
P.F.
,
Harpold
,
M.M.
et al.  (
2004
)
Modal gating of human CaV2.1 (P/Q-type) calcium channels: I. The slow and the fast gating modes and their modulation by beta subunits
.
J. Gen. Physiol.
124
,
445
461
33
Colecraft
,
H.M.
,
Alseikhan
,
B.
,
Takahashi
,
S.X.
,
Chaudhuri
,
D.
,
Mittman
,
S.
,
Yegnasubramanian
,
V.
et al.  (
2002
)
Novel functional properties of Ca(2+) channel beta subunits revealed by their expression in adult rat heart cells
.
J. Physiol.
541
,
435
452
34
Bichet
,
D.
,
Cornet
,
V.
,
Geib
,
S.
,
Carlier
,
E.
,
Volsen
,
S.
,
Hoshi
,
T.
et al.  (
2000
)
The I-II loop of the Ca2+ channel alpha1 subunit contains an endoplasmic reticulum retention signal antagonized by the beta subunit
.
Neuron
25
,
177
190
35
Cornet
,
V.
,
Bichet
,
D.
,
Sandoz
,
G.
,
Marty
,
I.
,
Brocard
,
J.
,
Bourinet
,
E.
et al.  (
2002
)
Multiple determinants in voltage-dependent P/Q calcium channels control their retention in the endoplasmic reticulum
.
Eur. J. Neurosci.
16
,
883
895
36
Altier
,
C.
,
Garcia-Caballero
,
A.
,
Simms
,
B.
,
You
,
H.
,
Chen
,
L.
,
Walcher
,
J.
et al.  (
2011
)
The Cavβ subunit prevents RFP2-mediated ubiquitination and proteasomal degradation of L-type channels
.
Nat. Neurosci.
14
,
173
180
37
Arias
,
J.M.
,
Murbartián
,
J.
,
Vitko
,
I.
,
Lee
,
J.H.
,
Perez-Reyes
,
E.
(
2005
)
Transfer of beta subunit regulation from high to low voltage-gated Ca2+ channels
.
FEBS Lett.
579
,
3907
3912
38
Fang
,
K.
,
Colecraft
,
H.M.
(
2011
)
Mechanism of auxiliary β-subunit-mediated membrane targeting of L-type (Ca(V)1.2) channels
.
J. Physiol.
589
,
4437
4455
39
Dolphin
,
A.C.
(
2013
)
The α2δ subunits of voltage-gated calcium channels
.
Biochim. Biophys. Acta
1828
,
1541
1549
40
Geisler
,
S.
,
Schöpf
,
C.L.
,
Obermair
,
G.J.
(
2015
)
Emerging evidence for specific neuronal functions of auxiliary calcium channel α2δ subunits
.
Gen. Physiol. Biophys.
34
,
105
118
41
Mould
,
J.
,
Yasuda
,
T.
,
Schroeder
,
C.I.
,
Beedle
,
A.M.
,
Doering
,
C.J.
,
Zamponi
,
G.W.
et al.  (
2004
)
The alpha2delta auxiliary subunit reduces affinity of omega-conotoxins for recombinant N-type (Cav2.2) calcium channels
.
J. Biol. Chem.
279
,
34705
34714
42
Davies
,
A.
,
Kadurin
,
I.
,
Alvarez-Laviada
,
A.
,
Douglas
,
L.
,
Nieto-Rostro
,
M.
,
Bauer
,
C.S.
et al.  (
2010
)
The alpha2delta subunits of voltage-gated calcium channels form GPI-anchored proteins, a posttranslational modification essential for function
.
Proc. Natl. Acad. Sci. U.S.A.
107
,
1654
1659
43
Marais
,
E.
,
Klugbauer
,
N.
,
Hofmann
,
F.
(
2001
)
Calcium channel alpha(2)delta subunits-structure and Gabapentin binding
.
Mol. Pharmacol.
59
,
1243
1248
44
Whittaker
,
C.A.
,
Hynes
,
R.O.
(
2002
)
Distribution and evolution of von Willebrand/integrin A domains: widely dispersed domains with roles in cell adhesion and elsewhere
.
Mol. Biol. Cell
13
,
3369
3387
45
Anantharaman
,
V.
,
Aravind
,
L.
(
2000
)
Cache–a signaling domain common to animal Ca(2+)-channel subunits and a class of prokaryotic chemotaxis receptors
.
Trends Biochem. Sci.
25
,
535
537
46
Chang
,
F.C.
,
Hosey
,
M.M.
(
1988
)
Dihydropyridine and phenylalkylamine receptors associated with cardiac and skeletal muscle calcium channels are structurally different
.
J. Biol. Chem.
263
,
18929
18937
47
Witcher
,
D.R.
,
De Waard
,
M.
,
Sakamoto
,
J.
,
Franzini-Armstrong
,
C.
,
Pragnell
,
M.
,
Kahl
,
S.D.
et al.  (
1993
)
Subunit identification and reconstitution of the N-type Ca2+ channel complex purified from brain
.
Science
261
,
486
489
48
Liu
,
H.
,
De Waard
,
M.
,
Scott
,
V.E.
,
Gurnett
,
C.A.
,
Lennon
,
V.A.
,
Campbell
,
K.P.
(
1996
)
Identification of three subunits of the high affinity omega-conotoxin MVIIC-sensitive Ca2+ channel
.
J. Biol. Chem.
271
,
13804
13810
49
Felix
,
R.
,
Gurnett
,
C.A.
,
De Waard
,
M.
,
Campbell
,
K.P.
(
1997
)
Dissection of functional domains of the voltage-dependent Ca2+ channel alpha2delta subunit
.
J. Neurosci.
17
,
6884
6891
50
Gao
,
B.
,
Sekido
,
Y.
,
Maximov
,
A.
,
Saad
,
M.
,
Forgacs
,
E.
,
Latif
,
F.
et al.  (
2000
)
Functional properties of a new voltage-dependent calcium channel alpha(2)delta auxiliary subunit gene (CACNA2D2)
.
J. Biol. Chem.
275
,
12237
12242
51
Yasuda
,
T.
,
Chen
,
L.
,
Barr
,
W.
,
McRory
,
J.E.
,
Lewis
,
R.J.
,
Adams
,
D.J.
et al.  (
2004
)
Auxiliary subunit regulation of high-voltage activated calcium channels expressed in mammalian cells
.
Eur. J. Neurosci.
20
,
1
13
52
Barclay
,
J.
,
Balaguero
,
N.
,
Mione
,
M.
,
Ackerman
,
S.L.
,
Letts
,
V.A.
,
Brodbeck
,
J.
et al.  (
2001
)
Ducky mouse phenotype of epilepsy and ataxia is associated with mutations in the Cacna2d2 gene and decreased calcium channel current in cerebellar Purkinje cells
.
J. Neurosci.
21
,
6095
6104
53
Brodbeck
,
J.
,
Davies
,
A.
,
Courtney
,
J.M.
,
Meir
,
A.
,
Balaguero
,
N.
,
Canti
,
C.
et al.  (
2002
)
The ducky mutation in Cacna2d2 results in altered Purkinje cell morphology and is associated with the expression of a truncated alpha 2 delta-2 protein with abnormal function
.
J. Biol. Chem.
277
,
7684
7693
54
Cantí
,
C.
,
Nieto-Rostro
,
M.
,
Foucault
,
I.
,
Heblich
,
F.
,
Wratten
,
J.
,
Richards
,
M.W.
et al.  (
2005
)
The metal-ion-dependent adhesion site in the Von Willebrand factor-A domain of alpha2delta subunits is key to trafficking voltage-gated Ca2+ channels
.
Proc. Natl. Acad. Sci. U.S.A.
102
,
11230
11235
55
Davies
,
A.
,
Douglas
,
L.
,
Hendrich
,
J.
,
Wratten
,
J.
,
Tran Van Minh
,
A.
,
Foucault
,
I.
et al.  (
2006
)
The calcium channel alpha2delta-2 subunit partitions with CaV2.1 into lipid rafts in cerebellum: implications for localization and function
.
J. Neurosci.
26
,
8748
8757
56
Hendrich
,
J.
,
Van Minh
,
A.T.
,
Heblich
,
F.
,
Nieto-Rostro
,
M.
,
Watschinger
,
K.
,
Striessnig
,
J.
et al.  (
2008
)
Pharmacological disruption of calcium channel trafficking by the alpha2delta ligand gabapentin
.
Proc. Natl. Acad. Sci. U.S.A.
105
,
3628
3633
57
Qin
,
N.
,
Olcese
,
R.
,
Stefani
,
E.
,
Birnbaumer
,
L.
(
1998
)
Modulation of human neuronal alpha 1E-type calcium channel by alpha 2 delta-subunit
.
Am. J. Physiol.
274
,
C1324
C1331
58
Kadurin
,
I.
,
Ferron
,
L.
,
Rothwell
,
S.W.
,
Meyer
,
J.O.
,
Douglas
,
L.R.
,
Bauer
,
C.S.
et al.  (
2016
)
Proteolytic maturation of α2δ represents a checkpoint for activation and neuronal trafficking of latent calcium channels
.
Elife
5
,
e21143
59
Bernstein
,
G.M.
,
Jones
,
O.T.
(
2007
)
Kinetics of internalization and degradation of N-type voltage-gated calcium channels: role of the alpha2/delta subunit
.
Cell Calcium
41
,
27
40
60
Hoppa
,
M.B.
,
Lana
,
B.
,
Margas
,
W.
,
Dolphin
,
A.C.
,
Ryan
,
T.A.
(
2012
)
α2δ expression sets presynaptic calcium channel abundance and release probability
.
Nature
486
,
122
125
61
Wu
,
J.
,
Yan
,
Z.
,
Li
,
Z.
,
Yan
,
C.
,
Lu
,
S.
,
Dong
,
M.
et al.  (
2015
)
Structure of the voltage-gated calcium channel Cav1.1 complex
.
Science
350
,
aad2395
62
Gurnett
,
C.A.
,
Felix
,
R.
,
Campbell
,
K.P.
(
1997
)
Extracellular interaction of the voltage-dependent Ca2+ channel alpha2delta and alpha1 subunits
.
J. Biol. Chem.
272
,
18508
18512
63
Field
,
M.J.
,
Li
,
Z.
,
Schwarz
,
J.B.
(
2007
)
Ca2+ channel alpha2-delta ligands for the treatment of neuropathic pain
.
J. Med. Chem.
50
,
2569
2575
64
Taylor
,
C.P.
,
Angelotti
,
T.
,
Fauman
,
E.
(
2007
)
Pharmacology and mechanism of action of pregabalin: the calcium channel alpha2-delta (alpha2-delta) subunit as a target for antiepileptic drug discovery
.
Epilepsy Res
73
,
137
150
65
Moore
,
R.A.
,
Wiffen
,
P.J.
,
Derry
,
S.
,
Toelle
,
T.
,
Rice
,
A.S.
(
2014
)
Gabapentin for chronic neuropathic pain and fibromyalgia in adults
.
Cochrane Database Syst. Rev.
66
Gee
,
N.S.
,
Brown
,
J.P.
,
Dissanayake
,
V.U.
,
Offord
,
J.
,
Thurlow
,
R.
,
Woodruff
,
G.N.
(
1996
)
The novel anticonvulsant drug, gabapentin (Neurontin), binds to the alpha2delta subunit of a calcium channel
.
J. Biol. Chem.
271
,
5768
5776
67
Gong
,
H.C.
,
Hang
,
J.
,
Kohler
,
W.
,
Li
,
L.
,
Su
,
T.Z.
(
2001
)
Tissue-specific expression and gabapentin-binding properties of calcium channel alpha2delta subunit subtypes
.
J. Membr. Biol.
184
,
35
43
68
Brown
,
J.P.
,
Gee
,
N.S.
(
1998
)
Cloning and deletion mutagenesis of the alpha2 delta calcium channel subunit from porcine cerebral cortex. Expression of a soluble form of the protein that retains [3H]gabapentin binding activity
.
J. Biol. Chem.
273
,
25458
25465
69
Wang
,
M.
,
Offord
,
J.
,
Oxender
,
D.L.
,
Su
,
T.Z.
(
1999
)
Structural requirement of the calcium-channel subunit alpha2delta for gabapentin binding
.
Biochem. J.
342
,
313
320
70
Bauer
,
C.S.
,
Nieto-Rostro
,
M.
,
Rahman
,
W.
,
Tran-Van-Minh
,
A.
,
Ferron
,
L.
,
Douglas
,
L.
et al.  (
2009
)
The increased trafficking of the calcium channel subunit alpha2delta-1 to presynaptic terminals in neuropathic pain is inhibited by the alpha2delta ligand pregabalin
.
J. Neurosci.
29
,
4076
4088
71
Tran-Van-Minh
,
A.
,
Dolphin
,
A.C.
(
2010
)
The alpha2delta ligand gabapentin inhibits the Rab11-dependent recycling of the calcium channel subunit alpha2delta-2
.
J. Neurosci.
30
,
12856
12867
72
Field
,
M.J.
,
Cox
,
P.J.
,
Stott
,
E.
,
Melrose
,
H.
,
Offord
,
J.
,
Su
,
T.Z.
et al.  (
2006
)
Identification of the alpha2-delta-1 subunit of voltage-dependent calcium channels as a molecular target for pain mediating the analgesic actions of pregabalin
.
Proc. Natl. Acad. Sci. U.S.A.
103
,
17537
17542
73
Klugbauer
,
N.
,
Dai
,
S.
,
Specht
,
V.
,
Lacinová
,
L.
,
Marais
,
E.
,
Bohn
,
G.
et al.  (
2000
)
A family of gamma-like calcium channel subunits
.
FEBS Lett.
470
,
189
197
74
Rousset
,
M.
,
Cens
,
T.
,
Restituito
,
S.
,
Barrere
,
C.
,
Black
,
J.L.
,
McEnery
,
M.W.
et al.  (
2001
)
Functional roles of gamma2, gamma3 and gamma4, three new Ca2+ channel subunits, in P/Q-type Ca2+ channel expressed in Xenopus oocytes
.
J. Physiol.
532
,
583
593
75
Green
,
P.J.
,
Warre
,
R.
,
Hayes
,
P.D.
,
McNaughton
,
N.C.
,
Medhurst
,
A.D.
,
Pangalos
,
M.
et al.  (
2001
)
Kinetic modification of the alpha(1I) subunit-mediated T-type Ca(2+) channel by a human neuronal Ca(2+) channel gamma subunit
.
J. Physiol.
533
,
467
478
76
Kang
,
M.G.
,
Chen
,
C.C.
,
Felix
,
R.
,
Letts
,
V.A.
,
Frankel
,
W.N.
,
Mori
,
Y.
et al.  (
2001
)
Biochemical and biophysical evidence for gamma 2 subunit association with neuronal voltage-activated Ca2+ channels
.
J. Biol. Chem.
276
,
32917
32924
77
Moss
,
F.J.
,
Dolphin
,
A.C.
,
Clare
,
J.J.
(
2003
)
Human neuronal stargazin-like proteins, gamma2, gamma3 and gamma4; an investigation of their specific localization in human brain and their influence on CaV2.1 voltage-dependent calcium channels expressed in Xenopus oocytes
.
BMC Neurosci.
4
,
23
78
Black
,
J.L.
(
2003
)
The voltage-gated calcium channel gamma subunits: a review of the literature
.
J. Bioenerg. Biomembr.
35
,
649
660
79
Letts
,
V.A.
(
2005
)
Stargazer–a mouse to seize
.
Epilepsy Curr.
5
,
161
165
80
Letts
,
V.A.
,
Felix
,
R.
,
Biddlecome
,
G.H.
,
Arikkath
,
J.
,
Mahaffey
,
C.L.
,
Valenzuela
,
A.
et al.  (
1998
)
The mouse stargazer gene encodes a neuronal Ca2+-channel gamma subunit
.
Nat. Genet.
19
,
340
347
81
Sharp
,
A.H.
,
Black
,
J.L.
,
Dubel
,
S.J.
,
Sundarraj
,
S.
,
Shen
,
J.P.
,
Yunker
,
A.M.
et al.  (
2001
)
Biochemical and anatomical evidence for specialized voltage-dependent calcium channel gamma isoform expression in the epileptic and ataxic mouse, stargazer
.
Neuroscience
105
,
599
617
82
Letts
,
V.A.
,
Kang
,
M.G.
,
Mahaffey
,
C.L.
,
Beyer
,
B.
,
Tenbrink
,
H.
,
Campbell
,
K.P.
et al.  (
2003
)
Phenotypic heterogeneity in the stargazin allelic series
.
Mamm. Genome
14
,
506
513
83
Zhang
,
Y.
,
Mori
,
M.
,
Burgess
,
D.L.
,
Noebels
,
J.L.
(
2002
)
Mutations in high-voltage-activated calcium channel genes stimulate low-voltage-activated currents in mouse thalamic relay neurons
.
J. Neurosci.
22
,
6362
6371
84
Moss
,
F.J.
,
Viard
,
P.
,
Davies
,
A.
,
Bertaso
,
F.
,
Page
,
K.M.
,
Graham
,
A.
et al.  (
2002
)
The novel product of a five-exon stargazin-related gene abolishes Ca(V)2.2 calcium channel expression
.
EMBO J.
21
,
1514
1523
85
Hansen
,
J.P.
,
Chen
,
R.S.
,
Larsen
,
J.K.
,
Chu
,
P.J.
,
Janes
,
D.M.
,
Weis
,
K.E.
et al.  (
2004
)
Calcium channel gamma6 subunits are unique modulators of low voltage-activated (Cav3.1) calcium current
.
J. Mol. Cell. Cardiol.
37
,
1147
1158
86
Lin
,
Z.
,
Witschas
,
K.
,
Garcia
,
T.
,
Chen
,
R.S.
,
Hansen
,
J.P.
,
Sellers
,
Z.M.
et al.  (
2008
)
A critical GxxxA motif in the gamma6 calcium channel subunit mediates its inhibitory effect on Cav3.1 calcium current
.
J. Physiol.
586
,
5349
5366
87
Chen
,
R.S.
,
Best
,
P.M.
(
2009
)
A small peptide inhibitor of the low voltage-activated calcium channel Cav3.1
.
Mol. Pharmacol.
75
,
1042
1051
88
Chen
,
L.
,
Chetkovich
,
D.M.
,
Petralia
,
R.S.
,
Sweeney
,
N.T.
,
Kawasaki
,
Y.
,
Wenthold
,
R.J.
et al.  (
2000
)
Stargazin regulates synaptic targeting of AMPA receptors by two distinct mechanisms
.
Nature
408
,
936
943
89
Tomita
,
S.
,
Fukata
,
M.
,
Nicoll
,
R.A.
,
Bredt
,
D.S.
(
2004
)
Dynamic interaction of stargazin-like TARPs with cycling AMPA receptors at synapses
.
Science
303
,
1508
1511
90
Körber
,
C.
,
Werner
,
M.
,
Kott
,
S.
,
Ma
,
Z.L.
,
Hollmann
,
M.
(
2007
)
The transmembrane AMPA receptor regulatory protein gamma 4 is a more effective modulator of AMPA receptor function than stargazin (gamma 2)
.
J. Neurosci.
27
,
8442
8447
91
Ferron
,
L.
,
Davies
,
A.
,
Page
,
K.M.
,
Cox
,
D.J.
,
Leroy
,
J.
,
Waithe
,
D.
et al.  (
2008
)
The stargazin-related protein gamma 7 interacts with the mRNA-binding protein heterogeneous nuclear ribonucleoprotein A2 and regulates the stability of specific mRNAs, including CaV2.2
.
J. Neurosci.
28
,
10604
10617
92
Tselnicker
,
I.
,
Tsemakhovich
,
V.A.
,
Dessauer
,
C.W.
,
Dascal
,
N.
(
2010
)
Stargazin modulates neuronal voltage-dependent Ca(2+) channel Ca(v)2.2 by a Gbetagamma-dependent mechanism
.
J. Biol. Chem.
285
,
20462
20471
93
Xia
,
Z.
,
Storm
,
D.R.
(
2005
)
The role of calmodulin as a signal integrator for synaptic plasticity
.
Nat. Rev. Neurosci.
6
,
267
276
94
Ben-Johny
,
M.
,
Yue
,
D.T.
(
2014
)
Calmodulin regulation (calmodulation) of voltage-gated calcium channels
.
J. Gen. Physiol.
143
,
679
692
95
Ben-Johny
,
M.
,
Dick
,
I.E.
,
Sang
,
L.
,
Limpitikul
,
W.B.
,
Kang
,
P.W.
,
Niu
,
J.
et al.  (
2015
)
Towards a unified theory of calmodulin regulation (calmodulation) of voltage-gated calcium and sodium channels
.
Curr. Mol. Pharmacol.
8
,
188
205
96
Soong
,
T.W.
,
Mori
,
M.X.
(
2016
)
Post-transcriptional modifications and “Calmodulation” of voltage-gated calcium channel function: reflections by two collaborators of David T Yue
.
Channels (Austin)
10
,
14
19
97
Bourdin
,
B.
,
Marger
,
F.
,
Wall-Lacelle
,
S.
,
Schneider
,
T.
,
Klein
,
H.
,
Sauvé
,
R.
et al.  (
2010
)
Molecular determinants of the CaVbeta-induced plasma membrane targeting of the CaV1.2 channel
.
J. Biol. Chem.
285
,
22853
22863
98
Gao
,
T.
,
Bunemann
,
M.
,
Gerhardstein
,
B.L.
,
Ma
,
H.
,
Hosey
,
M.M.
(
2000
)
Role of the C terminus of the alpha 1C (CaV1.2) subunit in membrane targeting of cardiac L-type calcium channels
.
J. Biol. Chem.
275
,
25436
25444
99
Brunet
,
S.
,
Scheuer
,
T.
,
Klevit
,
R.
,
Catterall
,
W.A.
(
2005
)
Modulation of CaV1.2 channels by Mg2+ acting at an EF-hand motif in the COOH-terminal domain
.
J. Gen. Physiol.
126
,
311
323
100
Dolmetsch
,
R.E.
,
Pajvani
,
U.
,
Fife
,
K.
,
Spotts
,
J.M.
,
Greenberg
,
M.E.
(
2001
)
Signaling to the nucleus by an L-type calcium channel-calmodulin complex through the MAP kinase pathway
.
Science
294
,
333
339
101
Peterson
,
B.Z.
,
Lee
,
J.S.
,
Mulle
,
J.G.
,
Wang
,
Y.
,
de Leon
,
M.
,
Yue
,
D.T.
(
2000
)
Critical determinants of Ca(2+)-dependent inactivation within an EF-hand motif of L-type Ca(2+) channels
.
Biophys. J.
78
,
1906
1920
102
Bernatchez
,
G.
,
Talwar
,
D.
,
Parent
,
L.
(
1998
)
Mutations in the EF-hand motif impair the inactivation of barium currents of the cardiac alpha1C channel
.
Biophys. J.
75
,
1727
1739
103
Brunet
,
S.
,
Scheuer
,
T.
,
Catterall
,
W.A.
(
2009
)
Cooperative regulation of Ca(v)1.2 channels by intracellular Mg(2+), the proximal C-terminal EF-hand, and the distal C-terminal domain
.
J. Gen. Physiol.
134
,
81
94
104
Benmocha
,
A.
,
Almagor
,
L.
,
Oz
,
S.
,
Hirsch
,
J.A.
,
Dascal
,
N.
(
2009
)
Characterization of the calmodulin-binding site in the N terminus of CaV1.2
.
Channels (Austin)
3
,
337
342
105
Dick
,
I.E.
,
Tadross
,
M.R.
,
Liang
,
H.
,
Tay
,
L.H.
,
Yang
,
W.
,
Yue
,
D.T.
(
2008
)
A modular switch for spatial Ca2+ selectivity in the calmodulin regulation of CaV channels
.
Nature
451
,
830
834
106
Simms
,
B.A.
,
Souza
,
I.A.
,
Zamponi
,
G.W.
(
2014
)
A novel calmodulin site in the Cav1.2 N-terminus regulates calcium-dependent inactivation
.
Pflügers Arch.
466
,
1793
1803
107
Simms
,
B.A.
,
Souza
,
I.A.
,
Rehak
,
R.
,
Zamponi
,
G.W.
(
2015
)
The Cav1.2 N terminus contains a CaM kinase site that modulates channel trafficking and function
.
Pflügers Arch.
467
,
677
686
108
Suzuki
,
H.
,
Kawai
,
J.
,
Taga
,
C.
,
Yaoi
,
T.
,
Hara
,
A.
,
Hirose
,
K.
et al.  (
1996
)
Stac, a novel neuron-specific protein with cysteine-rich and SH3 domains
.
Biochem. Biophys. Res. Commun.
229
,
902
909
109
Legha
,
W.
,
Gaillard
,
S.
,
Gascon
,
E.
,
Malapert
,
P.
,
Hocine
,
M.
,
Alonso
,
S.
et al.  (
2010
)
stac1 and stac2 genes define discrete and distinct subsets of dorsal root ganglia neurons
.
Gene Expr. Patterns
10
,
368
375
110
Horstick
,
E.J.
,
Linsley
,
J.W.
,
Dowling
,
J.J.
,
Hauser
,
M.A.
,
McDonald
,
K.K.
,
Ashley-Koch
,
A.
et al.  (
2013
)
Stac3 is a component of the excitation-contraction coupling machinery and mutated in Native American myopathy
.
Nat. Commun.
4
,
1952
111
Nelson
,
B.R.
,
Wu
,
F.
,
Liu
,
Y.
,
Anderson
,
D.M.
,
McAnally
,
J.
,
Lin
,
W.
et al.  (
2013
)
Skeletal muscle-specific T-tubule protein STAC3 mediates voltage-induced Ca2+ release and contractility
.
Proc. Natl. Acad. Sci. U.S.A.
110
,
11881
11886
112
Bower
,
N.I.
,
de la Serrana
,
D.G.
,
Cole
,
N.J.
,
Hollway
,
G.E.
,
Lee
,
H.T.
,
Assinder
,
S.
et al.  (
2012
)
Stac3 is required for myotube formation and myogenic differentiation in vertebrate skeletal muscle
.
J. Biol. Chem.
287
,
43936
43949
113
Polster
,
A.
,
Nelson
,
B.R.
,
Olson
,
E.N.
,
Beam
,
K.G.
(
2016
)
Stac3 has a direct role in skeletal muscle-type excitation-contraction coupling that is disrupted by a myopathy-causing mutation
.
Proc. Natl. Acad. Sci. U.S.A.
113
,
10986
10991
114
Polster
,
A.
,
Perni
,
S.
,
Bichraoui
,
H.
,
Beam
,
K.G.
(
2015
)
Stac adaptor proteins regulate trafficking and function of muscle and neuronal L-type Ca2+ channels
.
Proc. Natl. Acad. Sci. U.S.A.
112
,
602
606
115
Weiss
,
N.
(
2015
)
Stac gets the skeletal L-type calcium channel unstuck
.
Gen. Physiol. Biophys.
34
,
101
103
116
Vitko
,
I.
,
Bidaud
,
I.
,
Arias
,
J.M.
,
Mezghrani
,
A.
,
Lory
,
P.
,
Perez-Reyes
,
E.
(
2007
)
The I-II loop controls plasma membrane expression and gating of Ca(v)3.2 T-type Ca2+ channels: a paradigm for childhood absence epilepsy mutations
.
J. Neurosci.
27
,
322
330
117
Baumgart
,
J.P.
,
Vitko
,
I.
,
Bidaud
,
I.
,
Kondratskyi
,
A.
,
Lory
,
P.
,
Perez-Reyes
,
E.
(
2008
)
I-II loop structural determinants in the gating and surface expression of low voltage-activated calcium channels
.
PLoS One
3
,
e2976
118
Rzhepetskyy
,
Y.
,
Lazniewska
,
J.
,
Proft
,
J.
,
Campiglio
,
M.
,
Flucher
,
B.E.
,
Weiss
,
N.
(
2016
)
A Cav3.2/Stac1 molecular complex controls T-type channel expression at the plasma membrane
.
Channels (Austin)
10
,
346
354
119
Iftinca
,
M.C.
,
Altier
,
C.
(
2016
)
Stacking up Cav3.2 channels
.
Channels (Austin)
11
,
1
2
120
Aromolaran
,
K.A.
,
Benzow
,
K.A.
,
Cribbs
,
L.L.
,
Koob
,
M.D.
,
Piedras-Rentería
,
E.S.
(
2009
)
Kelch-like 1 protein upregulates T-type currents by an actin-F dependent increase in α(1H) channels via the recycling endosome
.
Channels (Austin)
3
,
402
412
121
Aromolaran
,
K.A.
,
Benzow
,
K.A.
,
Cribbs
,
L.L.
,
Koob
,
M.D.
,
Piedras-Rentería
,
E.S.
(
2010
)
T-type current modulation by the actin-binding protein Kelch-like 1
.
Am. J. Physiol. Cell Physiol.
298
,
C1353
C1362
122
Perissinotti
,
P.P.
,
Ethington
,
E.G.
,
Cribbs
,
L.
,
Koob
,
M.D.
,
Martin
,
J.
,
Piedras-Rentería
,
E.S.
(
2014
)
Down-regulation of endogenous KLHL1 decreases voltage-gated calcium current density
.
Cell Calcium
55
,
269
280
123
Perissinotti
,
P.P.
,
Ethington
,
E.A.
,
Almazan
,
E.
,
Martínez-Hernández
,
E.
,
Kalil
,
J.
,
Koob
,
M.D.
et al.  (
2014
)
Calcium current homeostasis and synaptic deficits in hippocampal neurons from Kelch-like 1 knockout mice
.
Front. Cell Neurosci.
8
,
444
124
Felix
,
R.
,
Weiss
,
N.
(
2016
)
Ubiquitination and proteasome-mediated degradation of voltage-gated Ca2+ channels and potential pathophysiological implications
.
Gen. Physiol. Biophys.
36
,
1
5
125
Hershko
,
A.
,
Ciechanover
,
A.
(
1998
)
The ubiquitin system
.
Annu. Rev. Biochem.
67
,
425
479
126
Rougier
,
J.S.
,
Albesa
,
M.
,
Abriel
,
H.
,
Viard
,
P.
(
2011
)
Neuronal precursor cell-expressed developmentally down-regulated 4-1 (NEDD4-1) controls the sorting of newly synthesized Ca(V)1.2 calcium channels
.
J. Biol. Chem.
286
,
8829
8838
127
Rougier
,
J.S.
,
Albesa
,
M.
,
Syam
,
N.
,
Halet
,
G.
,
Abriel
,
H.
,
Viard
,
P.
(
2015
)
Ubiquitin-specific protease USP2-45 acts as a molecular switch to promote α2δ-1-induced downregulation of Cav1.2 channels
.
Pflügers Arch.
467
,
1919
1929
128
Waithe
,
D.
,
Ferron
,
L.
,
Page
,
K.M.
,
Chaggar
,
K.
,
Dolphin
,
A.C.
(
2011
)
Beta-subunits promote the expression of Ca(V)2.2 channels by reducing their proteasomal degradation
.
J. Biol. Chem.
286
,
9598
9611
129
Page
,
K.M.
,
Rothwell
,
S.W.
,
Dolphin
,
A.C.
(
2016
)
The CaVβ subunit protects the I-II loop of the voltage-gated calcium channel CaV2.2 from proteasomal degradation but not oligoubiquitination
.
J. Biol. Chem.
291
,
20402
20416
130
Gandini
,
M.A.
,
Henríquez
,
D.R.
,
Grimaldo
,
L.
,
Sandoval
,
A.
,
Altier
,
C.
,
Zamponi
,
G.W.
et al.  (
2014
)
CaV2.2 channel cell surface expression is regulated by the light chain 1 (LC1) of the microtubule-associated protein B (MAP1B) via UBE2L3-mediated ubiquitination and degradation
.
Pflügers Arch.
466
,
2113
2126
131
Gandini
,
M.A.
,
Sandoval
,
A.
,
Zamponi
,
G.W.
,
Felix
,
R.
(
2014
)
The MAP1B-LC1/UBE2L3 complex catalyzes degradation of cell surface CaV2.2 channels
.
Channels (Austin)
8
,
452
457
132
Macabuag
,
N.
,
Dolphin
,
A.C.
(
2015
)
Alternative splicing in Ca(V)2.2 regulates neuronal trafficking via adaptor protein complex-1 adaptor protein motifs
.
J. Neurosci.
35
,
14636
14652
133
Marangoudakis
,
S.
,
Andrade
,
A.
,
Helton
,
T.D.
,
Denome
,
S.
,
Castiglioni
,
A.J.
,
Lipscombe
,
D.
(
2012
)
Differential ubiquitination and proteasome regulation of Ca(V)2.2 N-type channel splice isoforms
.
J. Neurosci.
32
,
10365
10369
134
García-Caballero
,
A.
,
Gadotti
,
V.M.
,
Stemkowski
,
P.
,
Weiss
,
N.
,
Souza
,
I.A.
,
Hodgkinson
,
V.
et al.  (
2014
)
The deubiquitinating enzyme USP5 modulates neuropathic and inflammatory pain by enhancing Cav3.2 channel activity
.
Neuron
83
,
1144
1158
135
Garcia-Caballero
,
A.
,
Gadotti
,
V.M.
,
Chen
,
L.
,
Zamponi
,
G.W.
(
2016
)
A cell-permeant peptide corresponding to the cUBP domain of USP5 reverses inflammatory and neuropathic pain
.
Mol. Pain
136
Gadotti
,
V.M.
,
Caballero
,
A.G.
,
Berger
,
N.D.
,
Gladding
,
C.M.
,
Chen
,
L.
,
Pfeifer
,
T.A.
et al.  (
2015
)
Small organic molecule disruptors of Cav3.2–USP5 interactions reverse inflammatory and neuropathic pain
.
Mol. Pain
11
,
12
137
Lazniewska
,
J.
,
Weiss
,
N.
(
2014
)
The ‘sweet’ side of ion channels
.
Rev. Physiol. Biochem. Pharmacol.
167
,
67
114
138
Park
,
H.J.
,
Min
,
S.H.
,
Won
,
Y.J.
,
Lee
,
J.H.
(
2015
)
Asn-linked glycosylation contributes to surface expression and voltage-dependent gating of Cav1.2 Ca2+ channel
.
J. Microbiol. Biotechnol.
25
,
1371
1379
139
Wang
,
M.C.
,
Collins
,
R.F.
,
Ford
,
R.C.
,
Berrow
,
N.S.
,
Dolphin
,
A.C.
,
Kitmitto
,
A.
(
2004
)
The three-dimensional structure of the cardiac L-type voltage-gated calcium channel: comparison with the skeletal muscle form reveals a common architectural motif
.
J. Biol. Chem.
279
,
7159
7168
140
Yunker
,
A.M.
,
Sharp
,
A.H.
,
Sundarraj
,
S.
,
Ranganathan
,
V.
,
Copeland
,
T.D.
,
McEnery
,
M.W.
(
2003
)
Immunological characterization of T-type voltage-dependent calcium channel CaV3.1 (alpha 1G) and CaV3.3 (alpha 1I) isoforms reveal differences in their localization, expression, and neural development
.
Neuroscience
117
,
321
335
141
Chen
,
Y.
,
Sharp
,
A.H.
,
Hata
,
K.
,
Yunker
,
A.M.
,
Polo-Parada
,
L.
,
Landmesser
,
L.T.
et al.  (
2007
)
Site-directed antibodies to low-voltage-activated calcium channel CaV3.3 (alpha1I) subunit also target neural cell adhesion molecule-180
.
Neuroscience
145
,
981
996
142
Weiss
,
N.
,
Black
,
S.A.
,
Bladen
,
C.
,
Chen
,
L.
,
Zamponi
,
G.W.
(
2013
)
Surface expression and function of Cav3.2 T-type calcium channels are controlled by asparagine-linked glycosylation
.
Pflügers Arch.
465
,
1159
1170
143
Orestes
,
P.
,
Osuru
,
H.P.
,
McIntire
,
W.E.
,
Jacus
,
M.O.
,
Salajegheh
,
R.
,
Jagodic
,
M.M.
et al.  (
2013
)
Reversal of neuropathic pain in diabetes by targeting glycosylation of Ca(V)3.2 T-type calcium channels
.
Diabetes
62
,
3828
3838
144
Lazniewska
,
J.
,
Rzhepetskyy
,
Y.
,
Zhang
,
F.X.
,
Zamponi
,
G.W.
,
Weiss
,
N.
(
2016
)
Cooperative roles of glucose and asparagine-linked glycosylation in T-type calcium channel expression
.
Pflügers Arch.
468
,
1837
1851
145
Jagodic
,
M.M.
,
Pathirathna
,
S.
,
Nelson
,
M.T.
,
Mancuso
,
S.
,
Joksovic
,
P.M.
,
Rosenberg
,
E.R.
et al.  (
2007
)
Cell-specific alterations of T-type calcium current in painful diabetic neuropathy enhance excitability of sensory neurons
.
J. Neurosci.
27
,
3305
3316
146
Messinger
,
R.B.
,
Naik
,
A.K.
,
Jagodic
,
M.M.
,
Nelson
,
M.T.
,
Lee
,
W.Y.
,
Choe
,
W.J.
et al.  (
2009
)
In vivo silencing of the Ca(V)3.2 T-type calcium channels in sensory neurons alleviates hyperalgesia in rats with streptozocin-induced diabetic neuropathy
.
Pain
145
,
184
195
147
Latham
,
J.R.
,
Pathirathna
,
S.
,
Jagodic
,
M.M.
,
Choe
,
W.J.
,
Levin
,
M.E.
,
Nelson
,
M.T.
et al.  (
2009
)
Selective T-type calcium channel blockade alleviates hyperalgesia in ob/ob mice
.
Diabetes
58
,
2656
2665
148
Duzhyy
,
D.E.
,
Viatchenko-Karpinski
,
V.Y.
,
Khomula
,
E.V.
,
Voitenko
,
N.V.
,
Belan
,
P.V.
(
2015
)
Upregulation of T-type Ca2+ channels in long-term diabetes determines increased excitability of a specific type of capsaicin-insensitive DRG neurons
.
Mol. Pain
11
,
29
149
Ondacova
,
K.
,
Karmazinova
,
M.
,
Lazniewska
,
J.
,
Weiss
,
N.
,
Lacinova
,
L.
(
2016
)
Modulation of Cav3.2 T-type calcium channel permeability by asparagine-linked glycosylation
.
Channels (Austin)
10
,
175
184
150
Gurnett
,
C.A.
,
De Waard
,
M.
,
Campbell
,
K.P.
(
1996
)
Dual function of the voltage-dependent Ca2+ channel alpha 2 delta subunit in current stimulation and subunit interaction
.
Neuron
16
,
431
440
151
Sandoval
,
A.
,
Oviedo
,
N.
,
Andrade
,
A.
,
Felix
,
R.
(
2004
)
Glycosylation of asparagines 136 and 184 is necessary for the alpha2delta subunit-mediated regulation of voltage-gated Ca2+ channels
.
FEBS Lett.
576
,
21
26
152
Andrade
,
A.
,
Sandoval
,
A.
,
González-Ramírez
,
R.
,
Lipscombe
,
D.
,
Campbell
,
K.P.
,
Felix
,
R.
(
2009
)
The alpha(2)delta subunit augments functional expression and modifies the pharmacology of Ca(V)1.3 L-type channels
.
Cell Calcium
46
,
282
292
153
Tétreault
,
M.P.
,
Bourdin
,
B.
,
Briot
,
J.
,
Segura
,
E.
,
Lesage
,
S.
,
Fiset
,
C.
et al.  (
2016
)
Identification of glycosylation sites essential for surface expression of the CaVα2δ1 subunit and modulation of the cardiac CaV1.2 channel activity
.
J. Biol. Chem.
291
,
4826
4843
154
Price
,
M.G.
,
Davis
,
C.F.
,
Deng
,
F.
,
Burgess
,
D.L.
(
2005
)
The alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor trafficking regulator “stargazin” is related to the claudin family of proteins by Its ability to mediate cell-cell adhesion
.
J. Biol. Chem.
280
,
19711
19720
155
Sandoval
,
A.
,
Andrade
,
A.
,
Beedle
,
A.M.
,
Campbell
,
K.P.
,
Felix
,
R.
(
2007
)
Inhibition of recombinant N-type Ca(V) channels by the gamma 2 subunit involves unfolded protein response (UPR)-dependent and UPR-independent mechanisms
.
J. Neurosci.
27
,
3317
3327
156
Obermair
,
G.J.
,
Szabo
,
Z.
,
Bourinet
,
E.
,
Flucher
,
B.E.
(
2004
)
Differential targeting of the L-type Ca2+ channel alpha 1C (CaV1.2) to synaptic and extrasynaptic compartments in hippocampal neurons
.
Eur. J. Neurosci.
19
,
2109
2122
157
Tippens
,
A.L.
,
Pare
,
J.F.
,
Langwieser
,
N.
,
Moosmang
,
S.
,
Milner
,
T.A.
,
Smith
,
Y.
et al.  (
2008
)
Ultrastructural evidence for pre- and postsynaptic localization of Cav1.2 L-type Ca2+ channels in the rat hippocampus
.
J. Comp. Neurol.
506
,
569
583
158
Barbado
,
M.
,
Fablet
,
K.
,
Ronjat
,
M.
,
De Waard
,
M.
(
2009
)
Gene regulation by voltage-dependent calcium channels
.
Biochim. Biophys. Acta
1793
,
1096
1104
159
Westenbroek
,
R.E.
,
Hell
,
J.W.
,
Warner
,
C.
,
Dubel
,
S.J.
,
Snutch
,
T.P.
,
Catterall
,
W.A.
(
1992
)
Biochemical properties and subcellular distribution of an N-type calcium channel alpha 1 subunit
.
Neuron
9
,
1099
1115
160
Westenbroek
,
R.E.
,
Hoskins
,
L.
,
Catterall
,
W.A.
(
1998
)
Localization of Ca2+ channel subtypes on rat spinal motor neurons, interneurons, and nerve terminals
.
J. Neurosci.
18
,
6319
6330
161
Westenbroek
,
R.E.
,
Sakurai
,
T.
,
Elliott
,
E.M.
,
Hell
,
J.W.
,
Starr
,
T.V.
,
Snutch
,
T.P.
et al.  (
1995
)
Immunochemical identification and subcellular distribution of the alpha 1A subunits of brain calcium channels
.
J. Neurosci.
15
,
6403
6418
162
Hell
,
J.W.
,
Westenbroek
,
R.E.
,
Warner
,
C.
,
Ahlijanian
,
M.K.
,
Prystay
,
W.
,
Gilbert
,
M.M.
et al.  (
1993
)
Identification and differential subcellular localization of the neuronal class C and class D L-type calcium channel alpha 1 subunits
.
J. Cell Biol.
123
,
949
962
163
Brice
,
N.L.
,
Dolphin
,
A.C.
(
1999
)
Differential plasma membrane targeting of voltage-dependent calcium channel subunits expressed in a polarized epithelial cell line
.
J. Physiol.
515
,
685
694
164
Wittemann
,
S.
,
Mark
,
M.D.
,
Rettig
,
J.
,
Herlitze
,
S.
(
2000
)
Synaptic localization and presynaptic function of calcium channel beta 4-subunits in cultured hippocampal neurons
.
J. Biol. Chem.
275
,
37807
37814
165
Etemad
,
S.
,
Obermair
,
G.J.
,
Bindreither
,
D.
,
Benedetti
,
A.
,
Stanika
,
R.
,
Di Biase
,
V.
et al.  (
2014
)
Differential neuronal targeting of a new and two known calcium channel β4 subunit splice variants correlates with their regulation of gene expression
.
J. Neurosci.
34
,
1446
1461
166
Jarvis
,
S.E.
,
Zamponi
,
G.W.
(
2005
)
Masters or slaves? Vesicle release machinery and the regulation of presynaptic calcium channels
.
Cell Calcium
37
,
483
488
167
Szabo
,
Z.
,
Obermair
,
G.J.
,
Cooper
,
C.B.
,
Zamponi
,
G.W.
,
Flucher
,
B.E.
(
2006
)
Role of the synprint site in presynaptic targeting of the calcium channel CaV2.2 in hippocampal neurons
.
Eur. J. Neurosci.
24
,
709
718
168
Zamponi
,
G.W.
(
2003
)
Regulation of presynaptic calcium channels by synaptic proteins
.
J. Pharmacol. Sci.
92
,
79
83
169
Mochida
,
S.
,
Westenbroek
,
R.E.
,
Yokoyama
,
C.T.
,
Zhong
,
H.
,
Myers
,
S.J.
,
Scheuer
,
T.
et al.  (
2003
)
Requirement for the synaptic protein interaction site for reconstitution of synaptic transmission by P/Q-type calcium channels
.
Proc. Natl. Acad. Sci. U.S.A.
100
,
2819
2824
170
Weiss
,
N.
,
Hameed
,
S.
,
Fernández-Fernández
,
J.M.
,
Fablet
,
K.
,
Karmazinova
,
M.
,
Poillot
,
C.
et al.  (
2012
)
A Ca(v)3.2/syntaxin-1A signaling complex controls T-type channel activity and low-threshold exocytosis
.
J. Biol. Chem.
287
,
2810
2818
171
Jacus
,
M.O.
,
Uebele
,
V.N.
,
Renger
,
J.J.
,
Todorovic
,
S.M.
(
2012
)
Presynaptic Cav3.2 channels regulate excitatory neurotransmission in nociceptive dorsal horn neurons
.
J. Neurosci.
32
,
9374
9382
172
Weiss
,
N.
,
Zamponi
,
G.W.
,
De Waard
,
M.
(
2012
)
How do T-type calcium channels control low-threshold exocytosis
.
Commun. Integr. Biol.
5
,
377
380
173
Weiss
,
N.
,
Zamponi
,
G.W.
(
2013
)
Control of low-threshold exocytosis by T-type calcium channels
.
Biochim. Biophys. Acta
1828
,
1579
1586
174
Maximov
,
A.
,
Bezprozvanny
,
I.
(
2002
)
Synaptic targeting of N-type calcium channels in hippocampal neurons
.
J. Neurosci.
22
,
6939
6952
175
Hu
,
Q.
,
Saegusa
,
H.
,
Hayashi
,
Y.
,
Tanabe
,
T.
(
2005
)
The carboxy-terminal tail region of human Cav2.1 (P/Q-type) channel is not an essential determinant for its subcellular localization in cultured neurones
.
Genes Cells
10
,
87
96
176
Zhang
,
H.
,
Maximov
,
A.
,
Fu
,
Y.
,
Xu
,
F.
,
Tang
,
T.S.
,
Tkatch
,
T.
et al.  (
2005
)
Association of CaV1.3 L-type calcium channels with Shank
.
J. Neurosci.
25
,
1037
1049
177
Sheets
,
L.
,
Trapani
,
J.G.
,
Mo
,
W.
,
Obholzer
,
N.
,
Nicolson
,
T.
(
2011
)
Ribeye is required for presynaptic Ca(V)1.3a channel localization and afferent innervation of sensory hair cells
.
Development
138
,
1309
1319
178
Morgans
,
C.W.
(
2001
)
Localization of the alpha(1F) calcium channel subunit in the rat retina
.
Invest. Ophthalmol. Vis. Sci.
42
,
2414
2418
179
Obermair
,
G.J.
,
Schlick
,
B.
,
Di Biase
,
V.
,
Subramanyam
,
P.
,
Gebhart
,
M.
,
Baumgartner
,
S.
et al.  (
2010
)
Reciprocal interactions regulate targeting of calcium channel beta subunits and membrane expression of alpha1 subunits in cultured hippocampal neurons
.
J. Biol. Chem.
285
,
5776
5791
180
McEnery
,
M.W.
,
Vance
,
C.L.
,
Begg
,
C.M.
,
Lee
,
W.L.
,
Choi
,
Y.
,
Dubel
,
S.J.
(
1998
)
Differential expression and association of calcium channel subunits in development and disease
.
J. Bioenerg. Biomembr.
30
,
409
418
181
Tanaka
,
O.
,
Sakagami
,
H.
,
Kondo
,
H.
(
1995
)
Localization of mRNAs of voltage-dependent Ca(2+)-channels: four subtypes of alpha 1- and beta-subunits in developing and mature rat brain
.
Brain Res. Mol. Brain Res.
30
,
1
16
182
Vance
,
C.L.
,
Begg
,
C.M.
,
Lee
,
W.L.
,
Haase
,
H.
,
Copeland
,
T.D.
,
McEnery
,
M.W.
(
1998
)
Differential expression and association of calcium channel alpha1B and beta subunits during rat brain ontogeny
.
J. Biol. Chem.
273
,
14495
14502
183
Campiglio
,
M.
,
Di Biase
,
V.
,
Tuluc
,
P.
,
Flucher
,
B.E.
(
2013
)
Stable incorporation versus dynamic exchange of β subunits in a native Ca2+ channel complex
.
J. Cell Sci.
126
,
2092
2101
184
Voigt
,
A.
,
Freund
,
R.
,
Heck
,
J.
,
Missler
,
M.
,
Obermair
,
G.J.
,
Thomas
,
U.
et al.  (
2016
)
Dynamic association of calcium channel subunits at the cellular membrane
.
Neurophotonics
3
,
041809
185
Kaur
,
G.
,
Pinggera
,
A.
,
Ortner
,
N.J.
,
Lieb
,
A.
,
Sinnegger-Brauns
,
M.J.
,
Yarov-Yarovoy
,
V.
et al.  (
2015
)
A polybasic plasma membrane binding motif in the I-II linker stabilizes voltage-gated CaV1.2 calcium channel function
.
J. Biol. Chem.
290
,
21086
21100
186
Scher
,
M.G.
,
Bloch
,
R.J.
(
1993
)
Phospholipid asymmetry in acetylcholine receptor clusters
.
Exp. Cell Res.
208
,
485
491
187
Zamponi
,
G.W.
(
2016
)
Targeting voltage-gated calcium channels in neurological and psychiatric diseases
.
Nat. Rev. Drug Discov.
15
,
19
34
This is an open access article published by Portland Press Limited on behalf of the Biochemical Society and distributed under the Creative Commons Attribution Licence 4.0 (CC BY).