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 (By similarity). 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 (By similarity).