3nif

The Closed Headpiece of Integrin IIb 3 and its Complex with an IIb 3 -Specific Antagonist That Does Not Induce Opening

spinqualitylabelsall models 3nif, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3nif is a 8 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.4Å Ligands: CA, GOL, MAN, MG, NAG, NIF, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease ITA2B_HUMAN 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. Function ITA2B_HUMAN 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. Publication Abstract from PubMed The platelet integrin alpha(IIb)beta(3) is essential for hemostasis and thrombosis through its binding of adhesive plasma proteins. We have determined crystal structures of the alpha(IIb)beta(3) headpiece in the absence of ligand and after soaking in RUC-1, a novel small molecule antagonist. In the absence of ligand, the alpha(IIb)beta(3) headpiece is in a closed conformation, distinct from the open conformation visualized in presence of Arg-Gly-Asp (RGD) antagonists. In contrast to RGD antagonists, RUC-1 binds only to the alpha(IIb) subunit. Molecular dynamics revealed nearly identical binding. Two species-specific residues, alpha(IIb) Y190 and alpha(IIb) D232, in the RUC-1 binding site were confirmed as important by mutagenesis. In sharp contrast to RGD-based antagonists, RUC-1 did not induce alpha(IIb)beta(3) to adopt an open conformation, as determined by gel filtration and dynamic light scattering. These studies provide insights into the factors that regulate integrin headpiece opening, and demonstrate the molecular basis for a novel mechanism of integrin antagonism. Closed headpiece of integrin alphaIIbbeta3 and its complex with an alphaIIbbeta3-specific antagonist that does not induce opening.,Zhu J, Zhu J, Negri A, Provasi D, Filizola M, Coller BS, Springer TA Blood. 2010 Dec 2;116(23):5050-9. Epub 2010 Aug 2. PMID:20679525 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Integrin 3D structures Monoclonal Antibodies 3D structures

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