Sarcoglycans are a family of membrane glycoproteins that associate to form the sarcoglycan protein complex, which is responsible for connecting the muscle fiber cytoskeleton to the extracellular matrix, thereby affording support and stability to the muscles. Gamma sarcoglycan is one of the proteins in this complex. The sarcoglycan complex, in fact is made up of two distinct sub-complexes, and the gamma sarcoglycan protein is an integral part of both these sub-complexes. Incidentally, SGCG interacts with the Filamin Gamma (FLNC) component of the sarcoglycan complex. This complex itself, interacts with other proteins like dystrophins, dystrophin associated glycoproteins, and dystroglycans to form the dystrophin-glycoprotein complex, which in turn functions to bind actin to the extracellular matrix of myocytes.
In patients with Limb Girdle Muscular Dystrophy, Type 2C, gamma sarcoglycan is absent from the myocyte membranes, thereby explaining the physiology of the disease.