GP1BA cDNA Clone – Glycoprotein Ib (Platelet), Alpha Polypeptide (Human)

Glycoprotein Ib (GP Ib) is a platelet surface membrane glycoprotein composed of a heterodimer, an alpha chain and a beta chain, that is linked by disulfide bonds. The Gp Ib functions as a receptor for von Willebrand factor (VWF). The complete receptor complex includes noncovalent association of the alpha and beta subunits with platelet glycoprotein IX and platelet glycoprotein V. The binding of the GP Ib-IX-V complex to VWF facilitates initial platelet adhesion to vascular subendothelium after vascular injury, and also initiates signaling events within the platelet that lead to enhanced platelet activation, thrombosis, and hemostasis. This gene encodes the alpha subunit. Mutations in this gene result in Bernard-Soulier syndromes and platelet-type von Willebrand disease. The coding region of this gene is known to contain a polymophic variable number tandem repeat (VNTR) domain that is associated with susceptibility to nonarteritic anterior ischemic optic neuropathy. [provided by RefSeq, Oct 2013]

GPIbA: GP-Ib, a surface membrane protein of platelets, participates in the formation of platelet plugs by binding to the A1 domain of vWF, which is already bound to the subendothelium. Genetic variations in GP1BA may be a cause of susceptibility to non-arteritic anterior ischemic optic neuropathy (NAION). NAION is an ocular disease due to ischemic injury to the optic nerve. It usually affects the optic disk and leads to visual loss and optic disk swelling of a pallid nature. Visual loss is usually sudden, or over a few days at most and is usually permanent, with some recovery possibly occurring within the first weeks or months. Patients with small disks having smaller or non-existent cups have an anatomical predisposition for non-arteritic anterior ischemic optic neuropathy. As an ischemic episode evolves, the swelling compromises circulation, with a spiral of ischemia resulting in further neuronal damage. Defects in GP1BA are a cause of Bernard-Soulier syndrome (BSS); also known as giant platelet disease (GPD). BSS patients have unusually large platelets and have a clinical bleeding tendency. Defects in GP1BA are the cause of benign mediterranean macrothrombocytopenia (BMM); also known as autosomal dominant benign Bernard-Soulier syndrome. BMM is characterized by mild or no clinical symptoms, normal platelet function, and normal megakaryocyte count. Defects in GP1BA are the cause of pseudo-von Willebrand disease (VWDP). A bleeding disorder is caused by an increased affinity of GP-Ib for soluble vWF resulting in impaired hemostatic function due to the removal of vWF from the circulation.

Protein type: Cell adhesion; Cell surface; Membrane protein, integral

Chromosomal Location of Human Ortholog: 17p13.2

Cellular Component: anchored to external side of plasma membrane; cell surface; cytoplasm; integral to plasma membrane; membrane; plasma membrane

Molecular Function: protein binding; protein kinase inhibitor activity; thrombin receptor activity

Biological Process: blood coagulation; blood coagulation, intrinsic pathway; cell adhesion; cell surface receptor linked signal transduction; cytokine and chemokine mediated signaling pathway; fibrinolysis; negative regulation of JAK-STAT cascade; negative regulation of protein kinase activity; platelet activation; regulation of blood coagulation

Disease: Bernard-soulier Syndrome; Bernard-soulier Syndrome, Type A2, Autosomal Dominant; Nonarteritic Anterior Ischemic Optic Neuropathy, Susceptibility To; Pseudo-von Willebrand Disease