Friday, October 12, 2012

Absence of Alpha-Sarcoglycans Related to Limb-Girdle Muscular Dystrophy

Dystrophin-glycoprotein complex bridges the inner cytoskeleton (F-actin) and the basal lamina. Mutations in all sarcoglycans, dysferlin, and caveolin-3, as well as mutations that cause abnormal glycosylation of alpha-dystroglycan can result in limb-girdle muscular dystrophy syndrome. Reprinted with permission from Cohn RD. Dystroglycan: important player in skeletal muscle and beyond. In: Neuromuscular Disorders. Vol. 15. Cohn RD. Elsevier; 2005: 207-17. 7, 20  

The sarcoglycans are a family of transmembrane proteins (α, β, γ, δ or ε) involved in the protein complex responsible for connecting the muscle fibre cytoskeleton to the extracellular matrix, preventing damage to the muscle fibre sarcolemma through shearing forces.
The dystrophin glycoprotein complex (DGC) is a membrane-spanning complex that links the interior cytoskeleton to the extracellular matrix in muscle. The sarcoglycan complex is a subcomplex within the DGC and is composed of several muscle-specific, transmembrane proteins (alpha-, beta-, gamma-, delta- and zeta-sarcoglycan). The sarcoglycans are asparagine-linked glycosylated proteins with single transmembrane domains.
The disorders caused by the mutations of the sarcoglycans are called sarcoglycanopathies. Mutations in the α, β, γ or δ genes (not ε) encoding these proteins can lead to the associated limb-girdle muscular dystrophy.

(Wikipedia)

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