NCIt definition : A heterotetrameric protein complex expressed on the surface of platelets that is involved
in promoting platelet adhesion to von Willebrand factor during wound healing. This
non-covalent complex is comprised of glycoprotein 5 (GPV; CD42d), glycoprotein 9 (GPIX;
CD42a), and glycoprotein Ib (GPIb). GPIb is a heterodimer comprised of platelet glycoprotein
Ib alpha chain (GPIba; CD42b) covalently bound to platelet glycoprotein Ib beta chain
(GPIbb; CD42c).;