Interaction between the Dihydropyridine Receptor Ca2+Channel$\beta-Subunit$and Ryanodine Receptor Type 1 Strengthens Excitation-Contraction Coupling
Previous studies have shown that the skeletal dihydropyridine receptor (DHPR) pore subunit$Ca_v1.1 (\alpha1S)$physically interacts with ryanodine receptor type 1 (RyR1), and a molecular signal is transmitted from$\alpha 1S$to RyR1 to trigger excitation-contraction (EC) coupling. We show that the$\be...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 102; no. 52; pp. 19225 - 19230 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
27.12.2005
National Acad Sciences |
Subjects | |
Online Access | Get full text |
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Summary: | Previous studies have shown that the skeletal dihydropyridine receptor (DHPR) pore subunit$Ca_v1.1 (\alpha1S)$physically interacts with ryanodine receptor type 1 (RyR1), and a molecular signal is transmitted from$\alpha 1S$to RyR1 to trigger excitation-contraction (EC) coupling. We show that the$\beta-subunit$of the skeletal DHPR also binds RyR1 and participates in this signaling process. A novel binding site for the DHPR$\beta 1a-subunit$was mapped to the$M^{3201}$to$W^{3661}$region of RyR1. In vitro binding experiments showed that the strength of the interaction is controlled by$K^{3495}KKRR\_\_R^{3502}$, a cluster of positively charged residues. Phenotypic expression of skeletal-type EC coupling by RyR1 with mutations in the$K^{3495}KKRR_R^{3502}$cluster was evaluated in dyspedic myotubes. The results indicated that charge neutralization or deletion severely depressed the magnitude of RyR1-mediated Ca2+transients coupled to voltage-dependent activation of the DHPR. Meantime the Ca2+content of the sarcoplasmic reticulum was not affected, and the amplitude and activation kinetics of the DHPR Ca2+currents were slightly affected. The data show that the DHPR$\beta-subunit$,$like \alpha 1S$, interacts directly with RyR1 and is critical for the generation of high-speed Ca2+signals coupled to membrane depolarization. These findings indicate that EC coupling in skeletal muscle involves the interplay of at least two subunits of the DHPR, namely$alpha 1S$and$\beta 1a$, interacting with possibly different domains of RyR1. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Abbreviations: DHPR, dihydropyridine receptor; RyR1, ryanodine receptor type 1; EC, excitation-contraction; SR, sarcoplasmic reticulum; GS, glutathione Sepharose; 4-CMC, 4-chloro-m-cresol. To whom correspondence should be addressed at: Institut National de la Santé et de la Recherche Médicale, Unité 607, Commissariat à l'Energie Atomique (CEA), Université Joseph Fourier, Laboratoire Canaux Calciques, Fonctions et Pathologies/Département de Réponse de Dynamique de Cellulaires, CEA Grenoble, 17 Rue des Martyrs, F 38054 Grenoble, France. E-mail: mronjat@cea.fr. Part of this data has been presented previously in abstract form [Cheng, W., Carbonneau, L., Sheridan, D., Keys, L., Altafaj, X., Ronjat, M. & Coronado, R. (2004) Biophys. J. 86, 220a (abstr.)]. Conflict of interest statement: No conflicts declared. Edited by Richard W. Tsien, Stanford University School of Medicine, Stanford, CA This paper was submitted directly (Track II) to the PNAS office. Author contributions: W.C., X.A., M.R., and R.C. designed research; W.C., X.A., and M.R. performed research; W.C. contributed new reagents/analytic tools; W.C., X.A., M.R., and R.C. analyzed data; and W.C., X.A., M.R., and R.C. wrote the paper. |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.0504334102 |