GP1BA

(redirected from GP1B)

GP1BA

A gene on chromosome 17pter-p12 that encodes the alpha subunit of the Ib-V-IX system of platelet surface membrane glycoproteins, which comprise the von Willebrand factor (vWF) receptor and mediate adhesion of platelets to injured vascular surfaces with circulation, a critical event in haemostasis. The alpha subunit provides the vWF binding site.

Molecular pathology
GP1BA polymorphisms and mutations are linked to Bernard-Soulier syndromes and platelet-type von Willebrand disease.
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At high shear rates, the platelet GP1b undergoes a conformational change, which promotes platelet adhesion to vWF.
Garfinkel et al., "VCL, an antagonist of the platelet GP1b receptor, markedly inhibits platelet adhesion and intimal thickening after balloon injury in the rat," Circulation, vol.
ADP: adenosine diphosphate; NO: nitric oxide; TXA2: thromboxane A2; GP1b: glycoprotein Ib; GPIIb/IIIa: glycoprotein IIb/IIIa; vWF: Von Willebrand factor; PDGF: platelet- derived growth factor.
VWF:Ag quantifies total VWF; VWF:RCo is a functional test in which VWF agglutinates platelets in the presence of ristocetin, which "activates" VWF, allowing it to interact with platelet GP1b (2).
VWF binds subendothelial collagen and adheres to platelets via the platelet GP1b receptor, which allows platelet clots to form at sites of injury.
The defect in type 2B VWD (5%-8% of all VWD cases) is a gain-of-function mutation in VWF that causes an increased affinity for the platelet GP1b receptor, resulting in continuous formation and clearance of VWF-platelet complexes (1-3).
Monomer Time x DP D[P.sub.CLMA] [F.sub.GMA] [M.sub.1]/ (h) (%) (c) (wt%) [M.sub.2] preMI1 CLMA/MMA 2.0 27 137 7 - MI1 preMI2 CLMA/lBMA 2.0 40 160 6 -- MI2 -- D[P.sub D[P.sub .graft] .GMA] GP1A GMA 1.0 15 13 92 45 GP1B 2.0 23 20 137 55 GP1C 3.0 36 31 217 66 GP2A GMA 1.0 15 14 87 34 GP2B 2.0 18 18 110 39 GP2C 3.0 23 23 139 45 No.
Causes of platalet number and function disorders Insufficient production * Hepatitis C in the bone marrow * Folic acid deficiency * Ethanol toxicity Increased destruction * Presence of autoantibody * DIC Dysfunction * Adhesion disorder * Aggregation disorder * Acquired storage pool disease * Decreased thromboxane A2 synthesis * Transmembrane conduction disorder * Decreased number of GP1b, GP2b3a deficiency (due to active fibrinolysis) * Increased HDL * Decreased hct * Increased endothelium-derived NO and prostocycline (the strongest platalet inhibitors)
a 2-Mpoint memory, segmented memory and waveform search, measurements + FFT, an MSO eight- or 16-channel option with serial bus analysis, a 3-MHz function generator option, a LAN/SVGA interface option, and a GP1B interface option.
In the assay plasma vWF binds to the platelet gp1b receptor on lyophilised reagent platelets and agglutinates the platelets in the presence of ristocetin.