1e03

PLASMA ALPHA ANTITHROMBIN-III AND PENTASACCHARIDE

spinqualitylabelsall models 1e03, resolution 2.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1e03 is a 2 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.9Å Ligands: BMA, GU1, GU6, NAG, Z9H, Z9K, Z9L Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease ANT3_HUMAN Defects in SERPINC1 are the cause of antithrombin III deficiency (AT3D) [MIM:613118. AT3D is an important risk factor for hereditary thrombophilia, a hemostatic disorder characterized by a tendency to recurrent thrombosis. AT3D is classified into 4 types. Type I: characterized by a 50% decrease in antigenic and functional levels. Type II: has defects affecting the thrombin-binding domain. Type III: alteration of the heparin-binding domain. Plasma AT-III antigen levels are normal in type II and III. Type IV: consists of miscellaneous group of unclassifiable mutations. [:] [:] Function ANT3_HUMAN Most important serine protease inhibitor in plasma that regulates the blood coagulation cascade. AT-III inhibits thrombin, matriptase-3/TMPRSS7, as well as factors IXa, Xa and XIa. Its inhibitory activity is greatly enhanced in the presence of heparin. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Antithrombin is a member of the serpin family of protease inhibitors and the major inhibitor of the blood coagulation cascade. It is unique amongst the serpins in that it circulates in a conformation that is inactive against its target proteases. Activation of antithrombin is brought about by a conformational change initiated upon binding heparin or heparan sulphate. Two isoforms exist in the circulation, alpha-antithrombin and beta-antithrombin, which differ in the amount of glycosylation present on the polypeptide chain; beta-antithrombin lacks the carbohydrate present at Asn135 in alpha-antithrombin. Of the two forms, beta-antithrombin has the higher affinity for heparin and thus functions as the major inhibitor in vivo even though it is the less abundant form. The reason for the differences in heparin affinity between the alpha and beta-forms have been shown to be due to the additional carbohydrate changing the rate of the conformational change. Here, we describe the most accurate structures of alpha-antithrombin and alpha-antithrombin+heparin pentasaccharide reported to date (2.6A and 2.9A resolution, respectively, both re-refinements using old data), and the structure of beta-antithrombin (2.6A resolution). The new structures have a remarkable degree of ordered carbohydrate and include parts of the antithrombin chain not modeled before. The structures have allowed a detailed comparison of the conformational differences between the three. They show that the structural basis of the lower affinity for heparin of alpha-antithrombin over beta-antithrombin is due to the conformational change that occurs upon heparin binding being sterically hindered by the presence of the additional bulky carbohydrate at Asn135. Structure of beta-antithrombin and the effect of glycosylation on antithrombin's heparin affinity and activity.,McCoy AJ, Pei XY, Skinner R, Abrahams JP, Carrell RW J Mol Biol. 2003 Feb 21;326(3):823-33. PMID:12581643 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Antithrombin 3D structures

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