- Dystrophin
Dystrophin is a rod-shaped
cytoplasmic protein , and a vital part of aprotein complex that connects thecytoskeleton of amuscle fiber to the surroundingextracellular matrix through thecell membrane . This complex is variously known as thecostamere or thedystrophin-associated protein complex . Many muscle proteins, such as α-dystrobrevin ,syncoilin ,synemin ,sarcoglycan ,dystroglycan , andsarcospan , colocalize with dystrophin at the costamere.As of 2007, dystrophin is the longest gene known, covering 2.4 megabases (0.08% of the human genome) at locus
Xp21 . Theprimary transcript measures about 2,400 kilobases and takes 16 hours to transcribe, the maturemRNA measures 14.0 kilobases [ [http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?val=NM_000109.2 NCBI Sequence Viewer v2.0 ] ] . The 79exons [Strachan T and Read AP, 1999. Human molecular genetics, BIOS Scientific, New York, USA] code for a protein of over 3500 amino acid residues. [ [http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?val=NP_000100.2 NCBI Sequence Viewer v2.0 ] ]Pathology
Its deficiency is one of the root causes of
muscular dystrophy . It was first identified in 1987 byLouis M. Kunkel [cite journal |author=Hoffman E, Brown R, Kunkel L |title=Dystrophin: the protein product of the Duchenne muscular dystrophy locus |journal=Cell |volume=51 |issue=6 |pages=919–28 |year=1987 |pmid=3319190 |doi=10.1016/0092-8674(87)90579-4] , after the 1986 discovery of the mutated gene that causesDuchenne muscular dystrophy (DMD) [cite journal |author=Monaco A, Neve R, Colletti-Feener C et al |title=Isolation of candidate cDNAs for portions of the Duchenne muscular dystrophy gene |journal=Nature |volume=323 |issue=6089 |pages=646–50 |year=1986 |pmid=3773991 |doi=10.1038/323646a0] .Normal tissue contains small amounts of dystrophin (about 0.002% of total muscle protein), but its absence leads to both DMD and
fibrosis , a condition of muscle hardening. A different mutation of the same gene causes defective dystrophin, leading toBecker's muscular dystrophy (BMD).Though its role in airway smooth muscle is not well established recent research indicates that dystrophin along with other subunits of dystrophin glycoprotein complex is associated with phenotype maturation. [cite journal |author=Sharma P, Tran T, Stelmack GL, "et al" |title=Expression of the dystrophin-glycoprotein complex is a marker for human airway smooth muscle phenotype maturation |journal=Am. J. Physiol. Lung Cell Mol. Physiol. |volume=294 |issue=1 |pages=L57–68 |year=2008 |pmid=17993586 |doi=10.1152/ajplung.00378.2007 |url=]
References
Further reading
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citations =
*cite journal | author=Roberts RG, Gardner RJ, Bobrow M |title=Searching for the 1 in 2,400,000: a review of dystrophin gene point mutations |journal=Hum. Mutat. |volume=4 |issue= 1 |pages= 1–11 |year= 1994 |pmid= 7951253 |doi= 10.1002/humu.1380040102
*cite journal | author=Tinsley JM, Blake DJ, Zuellig RA, Davies KE |title=Increasing complexity of the dystrophin-associated protein complex |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=91 |issue= 18 |pages= 8307–13 |year= 1994 |pmid= 8078878 |doi= 10.1073/pnas.91.18.8307
*cite journal | author=Blake DJ, Weir A, Newey SE, Davies KE |title=Function and genetics of dystrophin and dystrophin-related proteins in muscle |journal=Physiol. Rev. |volume=82 |issue= 2 |pages= 291–329 |year= 2002 |pmid= 11917091 |doi= 10.1152/physrev.00028.2001 |doi_brokendate=2008-06-22
*cite journal | author=Röper K, Gregory SL, Brown NH |title=The 'spectraplakins': cytoskeletal giants with characteristics of both spectrin and plakin families |journal=J. Cell. Sci. |volume=115 |issue= Pt 22 |pages= 4215–25 |year= 2003 |pmid= 12376554 |doi=
*cite journal | author=Muntoni F, Torelli S, Ferlini A |title=Dystrophin and mutations: one gene, several proteins, multiple phenotypes |journal=Lancet neurology |volume=2 |issue= 12 |pages= 731–40 |year= 2003 |pmid= 14636778 |doi= 10.1016/S1474-4422(03)00585-4
*cite journal | author=Haenggi T, Fritschy JM |title=Role of dystrophin and utrophin for assembly and function of the dystrophin glycoprotein complex in non-muscle tissue |journal=Cell. Mol. Life Sci. |volume=63 |issue= 14 |pages= 1614–31 |year= 2006 |pmid= 16710609 |doi= 10.1007/s00018-005-5461-0External links
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