Function: Protein C is a vitamin K-dependent serine protease that regulates blood coagulation by inactivating factors Va and VIIIa in the presence of calcium ions and phospholipids.
Catalytic activity: Degradation of blood coagulation factors Va and VIIIa.
Subunit structure: Synthesized as a single chain precursor, which is cleaved into a light chain and a heavy chain held together by a disulfide bond. The enzyme is then activated by thrombin, which cleaves a tetradecapeptide from the amino end of the heavy chain; this reaction, which occurs at the surface of endothelial cells, is strongly promoted by thrombomodulin.
Tissue specificity: Plasma; synthesized in the liver.
Post-translational modification: The vitamin K-dependent, enzymatic carboxylation of some Glu residues allows the modified protein to bind calcium.N- and O-glycosylated. Partial (70%) N-glycosylation of Asn-371 with an atypical N-X-C site produces a higher molecular weight form referred to as alpha. The lower molecular weight form, not N-glycosylated at Asn-371, is beta. O-glycosylated with core 1 or possibly core 8 glycans. Ref.12 Ref.15The iron and 2-oxoglutarate dependent 3-hydroxylation of aspartate and asparagine is (R) stereospecific within EGF domains.May be phosphorylated on a Ser or Thr in a region (AA 25-30) of the propeptide.
Involvement in disease: Thrombophilia due to protein C deficiency, autosomal dominant (THPH3) [MIM:176860]: A hemostatic disorder characterized by impaired regulation of blood coagulation and a tendency to recurrent venous thrombosis. Individuals with decreased amounts of protein C are classically referred to as having type I protein C deficiency and those with normal amounts of a functionally defective protein as having type II deficiency.Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.8 Ref.19 Ref.20 Ref.21 Ref.22 Ref.25 Ref.26 Ref.30 Ref.31 Ref.32 Ref.36 Ref.39 Ref.40 Ref.41Thrombophilia due to protein C deficiency, autosomal recessive (THPH4) [MIM:612304]: A hemostatic disorder characterized by impaired regulation of blood coagulation and a tendency to recurrent venous thrombosis. It results in a thrombotic condition that can manifest as a severe neonatal disorder or as a milder disorder with late-onset thrombophilia. The severe form leads to neonatal death through massive neonatal venous thrombosis. Often associated with ecchymotic skin lesions which can turn necrotic called purpura fulminans, this disorder is very rare.Note: The disease is caused by mutations affecting the gene represented in this entry.
Miscellaneous: Calcium also binds, with stronger affinity to another site, beyond the GLA domain. This GLA-independent binding site is necessary for the recognition of the thrombin-thrombomodulin complex.
Sequence similarities: Belongs to the peptidase S1 family.Contains 2 EGF-like domains.Contains 1 Gla (gamma-carboxy-glutamate) domain.Contains 1 peptidase S1 domain.
Sequence caution: The sequence S76088 differs from that shown. Reason: Erroneous termination at position 151. Translated as Cys.
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