Platelet Ca2+ signalling involves intracellular Ca2+ pools, whose content is controlled by sarco/endoplasmic reticulum Ca2+ATPases (SERCAs). Among these, a key role is played by the inositol trisphosphate-sensitive Ca2+ pool, associated with the SERCA 3b isoform. We have investigated the control of this Ca2+ pool through the cAMP-dependent phosphorylation of the GTP-binding protein, Rap (Ras-proximate) 1b. We first looked for this Ca2+ pool target of regulation by studying the expression of the different SERCA and Rap 1 proteins in human platelets and various cell lines, by Western blotting and reverse transcription-PCR. Since co-expression of Rap 1b and SERCA 3b was obtained, we looked for their protein–protein interaction as a function of the cAMP-dependent phosphorylation of Rap 1b. Co-immunoprecipitations of SERCA 3b and Rap 1b proteins were found in the absence of phosphorylation, induced by the catalytic subunit of the cAMP-dependent protein kinase (csPKA). In contrast, upon pre-treatment of platelet membranes with csPKA, the SERCA 3b dissociated from the Rap 1b protein, in agreement with a role of its phosphorylated state in their interaction. Finally, we looked for adaptation of this complex in a platelet pathological model of hypertension. We investigated the expression of both proteins, as well as the cAMP-dependent phosphorylation of Rap 1b and SERCA 3b activity in platelets from control normotensive Wistar-Kyoto rats and from spontaneously hypertensive rats (SHRs). A decrease in SERCA 3b activity was associated with a decrease in Rap 1b endogenous phosphorylation in SHR platelets, consistent with a functional role in the regulation of the SERCA 3b-associated Ca2+ pool.
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May 1998
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Research Article|
May 15 1998
Platelet sarco/endoplasmic reticulum Ca2+ATPase isoform 3b and Rap 1b: interrelation and regulation in physiopathology Available to Purchase
Christine LACABARATZ-PORRET;
Christine LACABARATZ-PORRET
1
*Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France
1To whom correspondence should be addressed (e-mail [email protected]).
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Elisabeth CORVAZIER;
Elisabeth CORVAZIER
*Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France
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Tünde KOVÀCS;
Tünde KOVÀCS
†National Institute of Haematology and Immunology, Daroczi ut 24, H-1113 Budapest, Hungary
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Régis BOBE;
Régis BOBE
*Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France
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Raymonde BREDOUX;
Raymonde BREDOUX
*Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France
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Sophie LAUNAY;
Sophie LAUNAY
*Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France
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Béla PAPP;
Béla PAPP
*Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France
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Jocelyne ENOUF
Jocelyne ENOUF
*Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France
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Publisher: Portland Press Ltd
Received:
July 31 1997
Revision Received:
February 18 1998
Accepted:
February 25 1998
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1998
1998
Biochem J (1998) 332 (1): 173–181.
Article history
Received:
July 31 1997
Revision Received:
February 18 1998
Accepted:
February 25 1998
Citation
Christine LACABARATZ-PORRET, Elisabeth CORVAZIER, Tünde KOVÀCS, Régis BOBE, Raymonde BREDOUX, Sophie LAUNAY, Béla PAPP, Jocelyne ENOUF; Platelet sarco/endoplasmic reticulum Ca2+ATPase isoform 3b and Rap 1b: interrelation and regulation in physiopathology. Biochem J 15 May 1998; 332 (1): 173–181. doi: https://doi.org/10.1042/bj3320173
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