Bovine Vitronectin Protein, CF

Vitronectin is a larger glycoprotein found in blood and in the extracellular matrix (ECM). The amino terminal segment of vitronectin harbors a binding site (aa 1 ‑ 44) for plasminogen activator inhibitor-1 (PAI‑1) and urokinase receptor, an Agr-Gly-ASP (RGD) sequence (aa 45 - 47) that provides a binding site for alpha _v beta ₃, alpha _v beta ₅, alpha _v beta ₁, alpha IIb beta ₃, alpha _v beta ₆, and alpha _v beta ₈ integrins, a stretch of acidic amino acids including two sulfated tyrosine residues (aa 56 and 59) that provide a binding site for thrombin-anti-thrombin III complexes, and a collagen binding site. The major part of the vitronecitn molecule (aa 132 - 459) accommodate six hemopexin repeats. The carboxyl-terminal end of vitronectin containing a stretch of basic amino acids (aa 348 - 379) that binds the acidic stretch of acidic amino acids in the amino-terminal section and stabilized vitronectin’s three dimensional structure. The carboxyl-terminal end of vitronectin also contains a plaminogen binding site (aa 332 ‑ 348), a heparin binding site that can be bound by complement factor C7, C8 or C9 (aa 348 ‑ 376), a glycosaminoglycan binding site (aa 348 ‑ 361), and a second PAI-1 binding site (aa 348 ‑ 370). Vitronectin also contains an endogenous cleavage site, two elastase cleavage sites, two thrombin cleavage sites, and a plasmin cleavage site. Vitronectin also has been shown to bind insulin growth factor II (IGF‑II) and TGF-beta. The apparent molecular weight of bovine vitronectin is 70 kDa, with ~15% of its molecular mass being contributed to by glycosylation. In blood and plasma, vitronectin is found predominantly as a single chain monomer. It can also be found as a dimer after endogenous cleavage. The dimer is comprised of a 65 kDa and 10 kDa component held together by a disulfide bond. Binding of thrombin-anti-thrombin II complex or complement lead to an unfolding of vitronectin. Unfolding of vitronectin leads to the formation of disulfide-linked multimers that are found in platelet releasate and in the extracellular matrix. Vitronectin is produced at high levels by the liver and many tumors. Vitronectin is involved in a number of biological functions including cell adhesion, cell spreading and migration, cell proliferation, extracellular anchoring, fibrinolysis, hemostasis, and complement immune defense.