2beh 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.
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.[1] [:][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] [:][23][24][25][26][27][28][29][30][31][32][33][34][35]
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.[36]
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
The poor inhibitory activity of circulating antithrombin (AT) is critical to the formation of blood clots at sites of vascular damage. AT becomes an efficient inhibitor of the coagulation proteases only after binding to a specific heparin pentasaccharide, which alters the conformation of the reactive center loop (RCL). The molecular basis of this activation event lies at the heart of the regulation of hemostasis and accounts for the anticoagulant properties of the low molecular weight heparins. Although several structures of AT have been solved, the conformation of the RCL in native AT remains unknown because of the obligate crystal contact between the RCL of native AT and its latent counterpart. Here we report the crystallographic structure of a variant of AT in its monomeric native state. The RCL shifted approximately 20 A, and a salt bridge was observed between the P1 residue (Arg-393) and Glu-237. This contact explains the effect of mutations at the P1 position on the affinity of AT for heparin and also the properties of AT-Truro (E237K). The relevance of the observed conformation was verified through mutagenesis studies and by solving structures of the same variant in different crystal forms. We conclude that the poor inhibitory activity of the circulating form of AT is partially conferred by intramolecular contacts that restrain the RCL, orient the P1 residue away from attacking proteases, and additionally block the exosite utilized in protease recognition.
Crystal structure of monomeric native antithrombin reveals a novel reactive center loop conformation.,Johnson DJ, Langdown J, Li W, Luis SA, Baglin TP, Huntington JA J Biol Chem. 2006 Nov 17;281(46):35478-86. Epub 2006 Sep 13. PMID:16973611[37]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
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↑Koide T, Odani S, Takahashi K, Ono T, Sakuragawa N. Antithrombin III Toyama: replacement of arginine-47 by cysteine in hereditary abnormal antithrombin III that lacks heparin-binding ability. Proc Natl Acad Sci U S A. 1984 Jan;81(2):289-93. PMID:6582486
↑Chang JY, Tran TH. Antithrombin III Basel. Identification of a Pro-Leu substitution in a hereditary abnormal antithrombin with impaired heparin cofactor activity. J Biol Chem. 1986 Jan 25;261(3):1174-6. PMID:3080419
↑Stephens AW, Thalley BS, Hirs CH. Antithrombin-III Denver, a reactive site variant. J Biol Chem. 1987 Jan 25;262(3):1044-8. PMID:3805013
↑Devraj-Kizuk R, Chui DH, Prochownik EV, Carter CJ, Ofosu FA, Blajchman MA. Antithrombin-III-Hamilton: a gene with a point mutation (guanine to adenine) in codon 382 causing impaired serine protease reactivity. Blood. 1988 Nov;72(5):1518-23. PMID:3179438
↑Erdjument H, Lane DA, Panico M, Di Marzo V, Morris HR. Single amino acid substitutions in the reactive site of antithrombin leading to thrombosis. Congenital substitution of arginine 393 to cysteine in antithrombin Northwick Park and to histidine in antithrombin Glasgow. J Biol Chem. 1988 Apr 25;263(12):5589-93. PMID:3162733
↑Erdjument H, Lane DA, Panico M, Di Marzo V, Morris HR, Bauer K, Rosenberg RD. Antithrombin Chicago, amino acid substitution of arginine 393 to histidine. Thromb Res. 1989 Jun 15;54(6):613-9. PMID:2781509
↑Borg JY, Brennan SO, Carrell RW, George P, Perry DJ, Shaw J. Antithrombin Rouen-IV 24 Arg----Cys. The amino-terminal contribution to heparin binding. FEBS Lett. 1990 Jun 18;266(1-2):163-6. PMID:2365065
↑Gandrille S, Aiach M, Lane DA, Vidaud D, Molho-Sabatier P, Caso R, de Moerloose P, Fiessinger JN, Clauser E. Important role of arginine 129 in heparin-binding site of antithrombin III. Identification of a novel mutation arginine 129 to glutamine. J Biol Chem. 1990 Nov 5;265(31):18997-9001. PMID:2229057
↑Austin RC, Rachubinski RA, Blajchman MA. Site-directed mutagenesis of alanine-382 of human antithrombin III. FEBS Lett. 1991 Mar 25;280(2):254-8. PMID:2013320
↑Perry DJ, Daly M, Harper PL, Tait RC, Price J, Walker ID, Carrell RW. Antithrombin Cambridge II, 384 Ala to Ser. Further evidence of the role of the reactive centre loop in the inhibitory function of the serpins. FEBS Lett. 1991 Jul 22;285(2):248-50. PMID:1906811
↑Olds RJ, Lane DA, Boisclair M, Sas G, Bock SC, Thein SL. Antithrombin Budapest 3. An antithrombin variant with reduced heparin affinity resulting from the substitution L99F. FEBS Lett. 1992 Apr 6;300(3):241-6. PMID:1555650
↑Blajchman MA, Fernandez-Rachubinski F, Sheffield WP, Austin RC, Schulman S. Antithrombin-III-Stockholm: a codon 392 (Gly----Asp) mutation with normal heparin binding and impaired serine protease reactivity. Blood. 1992 Mar 15;79(6):1428-34. PMID:1547341
↑Okajima K, Abe H, Maeda S, Motomura M, Tsujihata M, Nagataki S, Okabe H, Takatsuki K. Antithrombin III Nagasaki (Ser116-Pro): a heterozygous variant with defective heparin binding associated with thrombosis. Blood. 1993 Mar 1;81(5):1300-5. PMID:8443391
↑Olds RJ, Lane DA, Beresford CH, Abildgaard U, Hughes PM, Thein SL. A recurrent deletion in the antithrombin gene, AT106-108(-6 bp), identified by DNA heteroduplex detection. Genomics. 1993 Apr;16(1):298-9. PMID:8486379 doi:https://dx.doi.org/10.1006/geno.1993.1184
↑Emmerich J, Vidaud D, Alhenc-Gelas M, Chadeuf G, Gouault-Heilmann M, Aillaud MF, Aiach M. Three novel mutations of antithrombin inducing high-molecular-mass compounds. Arterioscler Thromb. 1994 Dec;14(12):1958-65. PMID:7981186
↑Millar DS, Wacey AI, Ribando J, Melissari E, Laursen B, Woods P, Kakkar VV, Cooper DN. Three novel missense mutations in the antithrombin III (AT3) gene causing recurrent venous thrombosis. Hum Genet. 1994 Nov;94(5):509-12. PMID:7959685
↑Jochmans K, Lissens W, Vervoort R, Peeters S, De Waele M, Liebaers I. Antithrombin-Gly 424 Arg: a novel point mutation responsible for type 1 antithrombin deficiency and neonatal thrombosis. Blood. 1994 Jan 1;83(1):146-51. PMID:8274732
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↑Okajima K, Abe H, Wagatsuma M, Okabe H, Takatsuki K. Antithrombin III Kumamoto II; a single mutation at Arg393-His increased the affinity of antithrombin III for heparin. Am J Hematol. 1995 Jan;48(1):12-8. PMID:7832187
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↑Johnson DJ, Langdown J, Li W, Luis SA, Baglin TP, Huntington JA. Crystal structure of monomeric native antithrombin reveals a novel reactive center loop conformation. J Biol Chem. 2006 Nov 17;281(46):35478-86. Epub 2006 Sep 13. PMID:16973611 doi:10.1074/jbc.M607204200
