Integrin alpha-IIb/beta-3 is a receptor for fibronectin, fibrinogen, plasminogen, prothrombin, thrombospondin and vitronectin. It recognizes the sequence R-G-D in a wide array of ligands. It recognizes the sequence H-H-L-G-G-G-A-K-Q-A-G-D-V in fibrinogen gamma chain. Following activation integrin alpha-IIb/beta-3 brings about platelet/platelet interaction through binding of soluble fibrinogen. This step leads to rapid platelet aggregation which physically plugs ruptured endothelial cell surface. Heterodimer of an alpha and a beta subunit. The alpha subunit is composed of a heavy and a light chain linked by a disulfide bond. Alpha-IIb associates with beta-3. Directly interacts with RNF181. Interacts (via C-terminus cytoplasmic tail region) with CIB1; the interaction is direct and calcium-dependent. Interacts (via C-terminus cytoplasmic tail region) with CIB2, CIB3 and CIB4; the interactions are stabilized/increased in a calcium and magnesium-dependent manner. ITGA2B:ITGB3 interacts with PPIA/CYPA; the interaction is ROS and PPIase activity-dependent and is increased in the presence of thrombin (By similarity). Isoform 1 and isoform 2 are expressed in platelets and megakaryocytes, but not in reticulocytes. Not detected in Jurkat, nor in U937 cell lines (PubMed:2351656). Isoform 3 is expressed in prostate adenocarcinoma, as well as in several erythroleukemia, prostate adenocarcinoma and melanoma cell lines, including PC-3, DU-145, HEL, WM983A, WM983B and WM35. Not detected in platelets, nor in normal prostate (at protein level) (PubMed:9809974). Position 874 is associated with platelet-specific alloantigen HPA-3/BAK/LEK. HPA-3A/BAK(A)/LEK(A) has Ile-874 and HPA-3B/BAK(B)/LEK(B) has Ser-874. HPA-3B is involved in neonatal alloimmune thrombocytopenia (NAIT or NATP). The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the integrin alpha chain family.