Sarcoglycan complex: A muscular supporter of dystroglycan-dystrophin interplay?

In striated muscle, the cytoskeletal protein dystrophin, the protein produc t of the Duchenne muscular dystrophy gene, is associated with a number of s arcolemmal glycoproteins to form a large oligomeric complex, the dystrophin -glycoprotein complex (DGC). Over the last 10 years, four of these sarcolem mal glycoproteins, alpha-, beta-, gamma- and delta-sarcoglycans, have been shown to form a distinct subcomplex, the sarcoglycan complex, in the DGC. F urthermore, the genetic defects of alpha-, beta-, gamma- and delta-sarcogly cans have been identified as the causes of four distinct forms of muscular dystrophies, which are now collectively called sarcoglycanopathy. Current s tudies are beginning to focus on the biological functions of the sarcoglyca n complex and the molecular mechanism by which its dysfunction leads to mus cle cell degeneration.