Synaptobrevin 2 (Sb2), syntaxin1 (Stx1), and synaptosomal-associated protein of 25kDa (SNAP-25) are the main components of the soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) complex involved in fusion of synaptic vesicles with the presynaptic plasma membrane. We report the characterization of D53, a novel SNARE-binding protein preferentially expressed in neural and neuro-endocrine cells. Its two-dimensional organization, established by the hydrophobic cluster analysis, is reminiscent of SNARE proteins. D53 contains two putative helical regions, one of which includes a large coiled-coil domain involved in the interaction with Sb2 in vitro. Following subcellular fractionation, endogenous D53 was specifically detected in the membrane-containing fraction of PC12 cells, where it co-immunoprecipitated with Sb2. Analysis by confocal microscopy showed that, in these cells, endogenous D53 co-localized partially with the transferrin receptor in early endosomes. In vitro assays revealed that binding properties of D53 to Stx1 and Sb2 are comparable with those of SNAP-25. Furthermore, D53 forms Sb2/Stx1/D53 complexes in vitro in a manner similar to SNAP-25. We propose that D53 could be involved in the assembly or disassembly of endosomal SNARE complexes by regulating Sb2/Stx interaction.
D53 is a novel endosomal SNARE-binding protein that enhances interaction of syntaxin 1 with the synaptobrevin 2 complex in vitro
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Véronique PROUX-GILLARDEAUX, Thierry GALLI, Isabelle CALLEBAUT, Anatoly MIKHAILIK, Georges CALOTHY, Maria MARX; D53 is a novel endosomal SNARE-binding protein that enhances interaction of syntaxin 1 with the synaptobrevin 2 complex in vitro. Biochem J 15 February 2003; 370 (1): 213–221. doi: https://doi.org/10.1042/bj20021309
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