Required for normal excitation-contraction coupling in skeletal muscle and for normal muscle contraction in response to membrane depolarization. Required for normal Ca(2+) release from the sarcplasmic reticulum, which ultimately leads to muscle contraction. Probably functions via its effects on muscle calcium channels (PubMed:23736855, PubMed:29078335). Increases CACNA1S channel activity, in addition to its role in enhancing the expression of CACNA1S at the cell membrane. Has a redundant role in promoting the expression of the calcium channel CACNA1S at the cell membrane (By similarity). Slows down the inactivation rate of the calcium channel CACNA1C (PubMed:29078335). Interacts (via SH3 domains) with the calcium channels CACNA1S and CACNA1C (PubMed:29078335). Component of a calcium channel complex with CACNA1S and CACNB1. Component of a calcium channel complex with CACNA1C and CACNB1 (By similarity). Co-localizes with CACNA1S and CACNA1C on T-tubules. The disease is caused by variants affecting the gene represented in this entry.