In genetic disorders of sarcoglycans a , b , and d sarcoglycan are found in similar levels in muscle. Filamins are involved in actin reorganization and signal transduction. They maintain membrane integrity during force application. It is a dual receptor for the G domain of Laminin 2 and agrin.
Mice lacking dystroglycan die as embryos and exhibit gross developmental abnormalities.
Selective depletion of dystroglycan in muscle produces a progressive myopathy with abnormal neuromuscular junctions. Muscle basement membranes are normal. The a 2 chain is abnormal or absent from muscle in some forms of congenital muscular dystrophy . Agrin has several variants depending on alternative mRNA splicing. Motor neurons contain 4 different agrin transcripts.