REA185 recognizes human CD42b, a 145 kDa, single-pass type I membrane protein. Expression of CD42b is found on platelets and megakaryocytes. CD42b, the α chain, together with the β chain (CD42c), forms the heterodimer, glycoprotein Ib (GP Ib). The GP Ib receptor complex further includes association of the alpha and beta subunits with platelet glycoprotein IX and glycoprotein V and this complex serves as the receptor for von Willebrand factor (VWF). The interaction of the GP Ib-IX-V complex to VWF initiates initial platelet adhesion to vascular subendothelium after vascular injury, platelet activation, thrombosis, and hemostasis. Other known ligands for GPIb–IX–V include α-thrombin, clotting factors XI/XIIa, and high-molecular weight kininogen. Additional information: Clone REA185 displays negligible binding to Fc receptors.
