Integrin alpha 2b (CD41) is a calcium-dependent，noncovalently associated heterodimer and contains a heavy chain (GPIIb alpha) and a light chain (GPIIb beta) linked by a single disulfide bond. The Integrin alpha 2B chain interacts with the Integrin beta 3 subunit/CD61 to form the platelet glycoprotein complex，gpIIb/IIIa. It is expressed on platelets and megakaryocytes. Ligands for the gpIIb/IIIa heterodimer include fibrinogen，von Willebrand factor，fibronectin，vitronectin，and thrombospondin. The gpIIb/IIIa complex is the major Integrin on platelets and is important for platelet adhesion and aggregation.