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Vitronectin also known as VTN is a protein that in humans is encoded by the ''VTN'' gene.〔(【引用サイトリンク】 url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=7448 )〕 The protein encoded by this gene is a member of the pexin family. Vitronectin is an abundant glycoprotein found in serum, the extracellular matrix and bone〔Boron, Walter F. and Boulpaep, Emile L. "Medical Physiology". Saunders, 2012, p.1097.〕 and promotes cell adhesion and spreading, inhibits the membrane-damaging effect of the terminal cytolytic complement pathway, and binds to several serpins (serine protease inhibitors). It is a secreted protein and exists in either a single chain form or a clipped, two chain form held together by a disulfide bond.〔 Vitronectin has been speculated to be involved in hemostasis and tumor malignancy. == Structure == Vitronectin is a 75 kDa glycoprotein, consisting of 459 amino acid residues. About one-third of the protein's molecular mass is composed of carbohydrates. On occasion, the protein is cleaved after arginine 379, to produce two-chain vitronectin, where the two parts are linked by a disulfide bond. No high resolution structure has been determined experimentally yet, except for the N-terminal domain. The protein consists of three domains: * The N-terminal Somatomedin B domain (1-39) * A central domains with hemopexin homology (131-342) * A C-terminal domain (residues 347-459) also with hemopexin homology. Several structures has been reported for the Somatomedin B domain. The protein was initially crystallized in complex with one of its physiological binding partners: the Plasminogen activator inhibitor-1 (PAI-1) and the structure solved for this complex. Subsequently two groups reported NMR structures of the domain. The Somatomedin B domain is a close-knit disulfide knot, with 4 disulfide bonds within 35 residues. Different disulfide configurations had been reported for this domain but this ambiguity has been resolved by the crystal structure.〔 Homology models have been built for the central and C-terminal domains.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Vitronectin」の詳細全文を読む スポンサード リンク
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