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first calponin homology (CH) domain found in dystrophin and similar proteins Dystrophin, encoded by the DMD gene, is a large, submembrane cytoskeletal protein that is the main component of the dystrophin-glycoprotein complex (DGC) in skeletal muscles. It links the transmembrane DGC to the actin cytoskeleton through binding strongly to the cytoplasmic tail of beta-dystroglycan, the transmembrane subunit of a highly O-glycosylated cell-surface protein. It is involved in maintaining the structural integrity of cells, as well as in the formation of the blood-brain barrier (BBB). Mutations in dystrophin lead to Duchenne muscular dystrophy (DMD). Moreover, dystrophin deficiency is associated with abnormal cerebral diffusion and perfusion, as well as in acute Trypanosoma cruzi infection. The dystrophin subfamily has been characterized by a compact cluster of domains comprising four EF-hand-like motifs and a ZZ-domain, followed by a looser region with two coiled-coils. These domains are believed to be involved in protein-protein interactions. In addition, dystrophin contains two syntrophin binding sites (SBSs) and a long N-terminal extension that comprises two actin-binding calponin homology (CH) domains, approximately 24 spectrin repeats (SRs) and a WW domain. This model corresponds to the first CH domain.
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