Dystrophin
| Dystrophin | ||
|---|---|---|
|
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| Dystrophin tetramer, human | ||
| Properties of human protein | ||
| Mass / length primary structure | 3685 amino acids | |
| Isoforms | 5 | |
| Identifier | ||
| Gene name | DMD | |
| External IDs | ||
| Occurrence | ||
| Homology family | Dystrophin | |
| Parent taxon | Vertebrates | |
Dystrophin is a protein in vertebrates that is found in the muscle fiber membrane ( sarcolemma ) and serves as a link between the contractile elements and the membrane system. It is therefore essential for muscle contraction. The protein was discovered in 1987 and in humans by the DMD - gene on the X chromosome encoded . With 2.5 million base pairs, DMD is the largest known human gene and makes up around 0.08% of the genome . The transcription of the gene alone takes 16 hours. Mutations in DMD can lead to the muscular dystrophy types Duchenne and Becker-Kiener, or to dilated cardiomyopathy (CMD3B).
Dystrophin is one of the clinically most important actin- binding proteins. Structurally it belongs to the spectrins .
function
Dystrophin functions intracellularly as a link between actin filament and beta- dystroglycan , a protein bridging the cell membrane , which in turn binds to the alpha-dystroglycan located outside the muscle cell. Alpha-dystroglycan is one of the most important receptors for proteins of the basement membrane and thus of the connective tissue surrounding the cells .
Via the dystroglycans, dystrophin is also connected to the sarcoglycan complex , which is also located in the membrane. Together, these proteins are also known as the dystrophin glycoprotein complex .
pathology
Deficiency, complete absence, or defects in the dystrophin glycoprotein complex lead to various forms of progressive muscular dystrophies , which are characterized by a rupture of the muscle fiber membrane and the release of the muscle enzyme creatine kinase . These diseases are associated with progressive muscle weakness and muscle wasting.