Functional equivalence of dihydropyridine receptor α1S and β1a subunits in excitationcontraction coupling in skeletal muscle

摘要

Molecular understanding of the mechanism of excitation-contraction (EC) coupling in skeletal muscle has been made possible by cultured myotube models lacking specific dihydropyridine receptor (DHPR) subunits and ryanodine receptor type 1 (RyR1) isoforms. Transient expression of missing cDNAs in mutant myotubes leads to a rapid recovery, within days, of various Ca2+ current and EC coupling phenotypes. These myotube models have thus permitted structure-function analysis of EC coupling domains present in the DHPR controlling the opening of RyR1. The purpose of this brief review is to highlight advances made by this laboratory towards understanding the contribution of domains present in the DHPR β1a subunit to EC coupling signaling. The evidence indicates that at least two subunits in the DHPR, namely α1S and β1a, control the signal transmitted to RyR1 during EC coupling.