ABSTRACT
The sarcoglycans are transmembrane proteins found as a plasma membrane-associated complex. First characterized as a subunit of the dystrophin glycoprotein complex in skeletal muscle, the sarcoglycan complex is secondary disrupted and destabilized from the plasma membrane when dystrophin is mutated, as in Duchenne Muscular Dystrophy. Autosomal recessive mutations in several sarcoglycan genes, OC, (3, y and 8, also lead to disrup tion of the sarcoglycan complex yielding a similar phenotype to what is seen in Duchenne Muscular Dystrophy and referred to as the type 2 Limb Girdle Muscular Dystrophies. Muta tions in 5-sarcoglycan have been reported in human cardiomyopathy patients. The exact func tion of the sarcoglycan complex is not known, but it appears to have both mechanical and nonmechanical roles in stabilizing the plasma membrane in cardiac and skeletal muscle. There is a variant of the sarcoglycan complex in vascular smooth muscle and in some nonmuscle cell and tissue types. Specifically, e-sarcoglycan is highly expressed in the central and peripheral nervous systems. Dominant mutations in e-sarcoglycan lead to an inherited movement disor der. Thus, the sarcoglycan complex has important roles in both muscle and nonmuscle tissues.
