Multiple Sequence Variants in STAC3 Affect Interactions with CaV1.1 and Excitation-Contraction Coupling

STAC3 is a soluble protein essential for skeletal muscle excitation-contraction (EC) coupling. Through its tandem SH3 domains, it interacts with the cytosolic II-III loop of the skeletal muscle voltage-gated calcium channel. STAC3 is the target for a mutation (W284S) that causes Native American myopathy, but multiple other sequence variants have been reported. Here, we report a crystal structure of the human STAC3 tandem SH3 domains. We analyzed...