CD41/Integrin alpha-IIb
CD41, the integrin alpha-IIb chain encoded by ITGA2B, teams with CD61 (beta3) to create platelet glycoprotein IIb/IIIa, the most abundant receptor on the platelet surface. Activated by inside-out signaling, alpha-IIb beta3 adopts a high-affinity conformation that bridges fibrinogen and von Willebrand factor between platelets, the obligatory final step of physiological aggregation. Biallelic mutations in ITGA2B or ITGB3 cause Glanzmann thrombasthenia, a bleeding disorder marked by absent clot retraction. The RGD- and fibrinogen-binding site is likewise the pharmacological target of abciximab, eptifibatide and tirofiban used in acute coronary syndromes, and megakaryocyte-specific CD41 expression makes it a lineage marker in thrombopoiesis research.
