Integrins are heterodimeric proteins made up of alpha and beta subunits. At least 18 alpha and 8 beta subunits have been described in mammals. Integrin family members are membrane receptors involved in cell adhesion and recognition in a variety of processes including embryogenesis, hemostasis, tissue repair, immune response and metastatic diffusion of tumor cells.

    
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.