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.