Integrin beta-3, also named as CD61 and GPIIIa, is a receptor for cytotactin, fibronectin, laminin, matrix metalloproteinase-2, osteopontin, osteomodulin, prothrombin, thrombospondin, vitronectin and von Willebrand factor. Integrin beta-3 recognize the sequence R-G-D in a wide array of ligands and the sequence H-H-L-G-G-G-A-K-Q-A-G-D-V in fibrinogen gamma chain. Following activation integrin beta-3 brings about platelet/platelet interaction through binding of soluble fibrinogen which leads to rapid platelet aggregation which physically plugs ruptured endothelial surface. In case of HIV-1 infection, the interaction with extracellular viral Tat protein seems to enhance angiogenesis in Kaposi's sarcoma lesions. Human integrin beta-3 has a calculated molecular weight of 87 kDa. As a result of glycosylation, the apparent molecular mass of integrin beta-3 is approximately 90-110 kDa.