Serpin C1/Antithrombin-III (SERPINC1) Active Protein

The protein encoded by this gene is a plasma protease inhibitor and a member of the serpin superfamily. This protein inhibits thrombin as well as other activated serine proteases of the coagulation system, and it regulates the blood coagulation cascade. The protein includes two functional domains: the heparin binding-domain at the N-terminus of the mature protein, and the reactive site domain at the C-terminus. The inhibitory activity is enhanced by the presence of heparin. More than 120 mutations have been identified for this gene, many of which are known to cause antithrombin-III deficiency. [provided by RefSeq, Jul 2009]

SERPINC1: 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. Defects in SERPINC1 are the cause of antithrombin III deficiency (AT3D). 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. Belongs to the serpin family.

Protein type: Secreted; Secreted, signal peptide; Inhibitor

Chromosomal Location of Human Ortholog: 1q25.1

Cellular Component: extracellular space; plasma membrane; extracellular region

Molecular Function: heparin binding; serine-type endopeptidase inhibitor activity; protein binding; protease binding

Biological Process: negative regulation of inflammatory response; blood coagulation; response to nutrient

Disease: Antithrombin Iii Deficiency