Component of the sarcoglycan complex, a subcomplex of the dystrophin-glycoprotein complex which forms a link between the F-actin cytoskeleton and the extracellular matrix. Interacts with the syntrophin SNTA1. Cross-link to form 2 major subcomplexes: one consisting of SGCB, SGCD and SGCG and the other consisting of SGCB and SGCD. The association between SGCB and SGCG is particularly strong while SGCA is loosely associated with the other sarcoglycans (By similarity). Most strongly expressed in skeletal muscle. Also expressed in cardiac muscle and, at much lower levels, in lung. In the fetus, most abundant in cardiac muscle and, at lower levels, in lung. Also detected in liver and kidney. Not expressed in brain. The disease is caused by variants affecting the gene represented in this entry. Belongs to the sarcoglycan alpha/epsilon family. SGCA mutations in LGMD2D