Functional roles of the gamma subunit of the skeletal muscle DHP-receptor

In excitation–contraction coupling (EC coupling) of skeletal muscle, large and rapid changes of the myoplasmic Ca²⁺ concentration mediate the activation and termination of force. The L-type Ca²⁺ channel (dihydropyridine receptor, DHP receptor) is a central component of the EC coupling process. Its predominant role is to provide the Ca²⁺ release channels of the sarcoplasmic reticulum (SR) with the sensitivity to cell membrane voltage. The DHP receptor consists of five different proteins (α_1S, β₁, γ₁, δ and α₂) whose tasks and functional characteristics are still incompletely understood. This short review summarizes progress made in studying the physiology of the γ₁ subunit, a membrane polypeptide that is highly specific for skeletal muscle. The focus is on recent results obtained from muscle of γ₁-deficient mice.