The GPIb-V-IX complex functions as the vWF receptor and mediates vWF-dependent platelet adhesion to blood vessels. The adhesion of platelets to injured vascular surfaces in the arterial circulation is a critical initiating event in hemostasis. GP-IX may provide for membrane insertion and orientation of GP-Ib. Two GP-Ib beta are disulfide-linked to one GP-Ib alpha. GP-IX is complexed with the GP-Ib heterodimer via a non covalent linkage. The disease is caused by variants affecting the gene represented in this entry. Platelet activation apparently involves disruption of the macromolecular complex of GP-Ib with the platelet glycoprotein IX (GP-IX) and dissociation of GP-Ib from the actin-binding protein.