CD61/Integrin beta 3
CD61, the integrin beta 3 chain, participates in two receptor systems: paired with alpha IIb it forms the platelet-specific fibrinogen receptor GPIIb/IIIa, and with alpha V (CD51) it forms the vitronectin receptor on platelets, endothelial and tumor cells. Inside-out signals during platelet activation switch the receptor to a high-affinity state that binds fibrinogen, von Willebrand factor and fibronectin, mediating platelet aggregation and thrombus growth; alpha IIb beta 3 antagonists such as abciximab exploit this step in acute coronary care. Germ-line ITGB3 mutations cause Glanzmann thrombasthenia, and antibodies against CD61 define this bleeding disorder diagnostically.
