Integrin alpha V chain interacts with the integrin beta 3 subunit/CD61 to form the alpha-V-beta-3 heterodimer/vitronectin receptor. It is expressed on endothelial cells，some activated leukocytes，NK cells，macrophages，neutrophils，and platelets. Integrin alpha V also forms heterodimers with the integrin beta 1，beta 5，beta 6，and beta 8 subunits. Alpha-V-beta-3 is an activation dependent receptor for platelet attachment and spreading on vitronectin and other matrix components. In case of HIV-1 infection，the interaction with extracellular viral Tat protein seems to enhance angiogenesis in Kaposi's sarcoma lesions. Alpha-V/beta-6 binds to foot-and-mouth disease virus (FMDV) VP1 protein and acts as a receptor for this virus By similarity. Alpha-V/beta-6 binds to coxsackievirus A9 and coxsackievirus B1 capsid proteins and acts as a receptor for these viruses.