The role of auxiliary dihydropyridine receptor subunits in muscle.

The skeletal muscle dihydropyridine receptor is a slowly-activating calcium channel that functions as the voltage sensor in excitation-contraction coupling. In addition to the pore-forming alpha(1S) subunit it contains the transmembrane alpha(2)delta-1 and gamma(1) subunits and the cytoplasmic beta(1a) subunit. Although the roles of the auxiliary subunits in calcium channel function have been intensively studied in heterologous expression systems, their functions in excitation-contraction coupling has only recently been elucidated in muscle cells of various null-mutant animal models. In this article we will briefly outline the current state of these investigations.