STAC (SH3 and Cysteine-Rich Domain): STAC, specifically STAC3 in humans, is a protein that plays a significant role in muscle contraction and function. It is involved in the excitation-contraction coupling of skeletal muscles. Mutations in the STAC3 gene are known to cause Native American myopathy, a rare congenital disorder characterized by muscle weakness, skeletal abnormalities, and susceptibility to malignant hyperthermia. The study of STAC3 is crucial for understanding muscle physiology and related disorders....