Vitronectin binds to activated human platelets and plays a role in platelet aggregation.
AUTOR(ES)
Asch, E
RESUMO
Vitronectin (Vn) is a multifunctional 75-kD glycoprotein that is present in plasma and the extracellular matrix. Vn functions as a complement regulatory protein in plasma, and promotes the growth and attachment of cells in tissue culture. Recent cDNA cloning reveals that like other adhesive proteins, Vn contains the sequence Arg-Gly-Asp and binds to some members of the integrin class of adhesive membrane receptors. In liposomes, the platelet membrane glycoprotein complex IIb/IIIa binds Vn, as well as fibrinogen, von Willebrand factor, and fibronectin. We examined the binding of purified Vn to resting and stimulated human platelets. Vn bound to thrombin-stimulated platelets in a calcium-dependent, specific, and saturable manner with a Kd of 320 nM and 8,000 sites per platelet. Epinephrine or ADP stimulation led to specific binding with KdS of 93 and 116 nM, respectively. Binding was inhibited by the tetrapeptide Arg-Gly-Asp-Ser and by monoclonal and polyclonal antibodies to GPIIb/IIIa. Endogenous platelet Vn stores were identified in immunoblots of gel-filtered platelets and the surface expression of endogenous platelet Vn was thrombin inducible. Monoclonal as well as polyclonal antibodies to Vn inhibited platelet aggregation, suggesting that Vn plays a role in the formation of stable platelet aggregates.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=296582Documentos Relacionados
- Aggregation and disaggregation kinetics of human blood platelets: Part II. Shear-induced platelet aggregation.
- Role of thrombospondin in platelet aggregation.
- Role of fibrinogen alpha and gamma chain sites in platelet aggregation.
- A monoclonal antibody against human thrombospondin inhibits platelet aggregation.
- Collagen-mediated platelet aggregation. Evidence for multivalent interactions of intermediate specificity between collagen and platelets.