Integrin alpha 2b beta 3, also known as GPIIbIIIa, is the most abundant Integrin expressed by megakaryocytes and platelets, both on the surface and within alpha granules. Deficiencies of alpha 2b beta 3 produce Glanzmann thrombasthenia, a potentially serious bleeding disorder. Active cell surface alpha 2b beta 3 adheres to Fibrinogen, mediating platelet/platelet interactions that initiate a cascade of platelet activation and aggregation, extracellular matrix adhesion, formation of thrombi, and clot retraction. It also binds matrix proteins that have an RGD motif, including Fibronectin, Plasminogen, Prothrombin, Thrombospondin, and Vitronectin.
