Platelet glycoprotein Ib alpha (GPIbα)

Platelet glycoprotein Ib alpha (GPIbα) is the largest and primary ligand-binding subunit of the GPIb-IX-V receptor complex, expressed on the platelet membrane[1][3][5]. It is crucial for platelet adhesion to sites of vascular injury by mediating the interaction with von Willebrand factor (VWF), especially under conditions of high shear stress, enabling the initial tethering and rolling of platelets on the vessel wall[1][4]. Its extracellular N-terminal domain contains seven leucine-rich repeats responsible for VWF binding, and its mucin-like region is highly glycosylated, keeping the ligand binding site accessible above the platelet surface[1][2][3]. GPIbα also binds other ligands, including thrombin, P-selectin, and Mac-1, and is involved in platelet-mediated thrombosis, vascular inflammation, and regulating signals essential to hemostasis[5][6][7]. Defects or loss of GPIbα function lead to bleeding disorders such as Bernard-Soulier syndrome, while overactivity contributes to arterial thrombosis[5][3]. Pharmacological targeting of GPIbα, as with caplacizumab or anfibatide, aims to modulate platelet–VWF interaction for therapeutic benefit, but carries a risk of bleeding and thrombocytopenia due to its central hemostatic role[5].

Other names

CD42bGlycoprotein IbαGPIb alpha chainGP1BAPlatelet receptor for von Willebrand factor

Inhibition of platelet adhesion to injured vessel walls (e.g., by blocking GPIbα–von Willebrand factor interaction) - Inhibition of platelet aggregation