Four sarcoglycan subunit proteins, designated alpha-, beta-, gamma - and delta-sarcoglycan, form a complex on the skeletal muscle cell surface membrane. A genetic defect in any one of these proteins causes the loss or marked decrease of the whole sarcoglycan complex, which is observed in the autosomal recessive muscular dystrophy, sarcoglycanopathy. In smooth muscle, beta- and delta-sarcoglycans are associated with E-sarcoglycan, a glycoprotein homologous to alpha-sarcoglycan. Additionally, a complete deficiency in delta-sarcoglycan is the cause of the Syrian hamster BIO.14 cardiomyopathy.