GPIIIbGPIIb

GPIIbGPIIb, also known as integrin alpha-IIb beta-3 or ITGA2B/ITGB3, is a protein complex found on the surface of platelets. It is a member of the integrin family of cell adhesion molecules. The GPIIbGPIIb receptor is formed by the non-covalent association of two transmembrane glycoproteins, the alpha-IIb subunit (CD41) and the beta-3 subunit (CD61). This heterodimer plays a critical role in hemostasis, the process of stopping bleeding.

Upon platelet activation, typically triggered by vascular injury, GPIIbGPIIb undergoes a conformational change. This change allows it to bind to its natural ligands, which are soluble proteins circulating in the blood plasma. The most important of these ligands is fibrinogen. Other ligands include von Willebrand factor and fibronectin. By binding fibrinogen, activated GPIIbGPIIb receptors on adjacent platelets can cross-link, forming a stable platelet aggregate. This aggregate is the primary component of a hemostatic plug, which seals damaged blood vessels.

Mutations in the genes encoding either the alpha-IIb or beta-3 subunits can lead to a severe bleeding disorder called Glanzmann thrombasthenia. In this condition, the GPIIbGPIIb receptor is either absent or non-functional, impairing platelet aggregation and leading to excessive bleeding. Due to its crucial role in platelet aggregation, GPIIbGPIIb is also a target for antiplatelet drugs, such as abciximab, which are used to prevent blood clots in patients with cardiovascular disease.