ID:ITA2B_HUMAN DESCRIPTION: RecName: Full=Integrin alpha-IIb; AltName: Full=GPalpha IIb; Short=GPIIb; AltName: Full=Platelet membrane glycoprotein IIb; AltName: CD_antigen=CD41; Contains: RecName: Full=Integrin alpha-IIb heavy chain; Contains: RecName: Full=Integrin alpha-IIb light chain, form 1; Contains: RecName: Full=Integrin alpha-IIb light chain, form 2; Flags: Precursor; FUNCTION: Integrin alpha-IIb/beta-3 is a receptor for fibronectin, fibrinogen, plasminogen, prothrombin, thrombospondin and vitronectin. It recognizes the sequence R-G-D in a wide array of ligands. It recognizes the sequence H-H-L-G-G-G-A-K-Q-A-G-D-V in fibrinogen gamma chain. Following activation integrin alpha- IIb/beta-3 brings about platelet/platelet interaction through binding of soluble fibrinogen. This step leads to rapid platelet aggregation which physically plugs ruptured endothelial cell surface. SUBUNIT: Heterodimer of an alpha and a beta subunit. The alpha subunit is composed of an heavy and a light chain linked by a disulfide bond. Alpha-IIb associates with beta-3. Directly interacts with RNF181. INTERACTION: Self; NbExp=7; IntAct=EBI-702693, EBI-702693; P05106:ITGB3; NbExp=3; IntAct=EBI-702693, EBI-702847; SUBCELLULAR LOCATION: Membrane; Single-pass type I membrane protein. TISSUE SPECIFICITY: Isoform 1 and isoform 2 were identified in platelets and megakaryocytes, but not in reticulocytes or in Jurkat and U-937 white blood cell line. Isoform 3 is expressed by leukemia, prostate adenocarcinoma and melanoma cells but not by platelets or normal prostate or breast epithelial cells. POLYMORPHISM: Position 874 is associated with platelet-specific alloantigen HPA-3/BAK/LEK. HPA-3A/BAK(A)/LEK(A) has Ile-874 and HPA-3B/BAK(B)/LEK(B) has Ser-874. HPA-3B is involved in neonatal alloimmune thrombocytopenia (NAIT or NATP). DISEASE: Defects in ITGA2B are a cause of Glanzmann thrombasthenia (GT) [MIM:273800]; also known as thrombasthenia of Glanzmann and Naegeli. GT is the most common inherited disease of platelets. It is an autosomal recessive disorder characterized by mucocutaneous bleeding of mild-to-moderate severity and the inability of this integrin to recognize macromolecular or synthetic peptide ligands. GT has been classified clinically into types I and II. In type I, platelets show absence of the glycoprotein IIb/beta-3 complexes at their surface and lack fibrinogen and clot retraction capability. In type II, the platelets express the glycoprotein IIb/beta-3 complex at reduced levels (5-20% controls), have detectable amounts of fibrinogen, and have low or moderate clot retraction capability. The platelets of GT 'variants' have normal or near normal (60-100%) expression of dysfunctional receptors. SIMILARITY: Belongs to the integrin alpha chain family. SIMILARITY: Contains 7 FG-GAP repeats. WEB RESOURCE: Name=GeneReviews; URL="http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/gene/ITGA2B";
Protein Domain and Structure Information
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