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 (PubMed:25618265). Exerts a protective effect on the endothelial cell barrier function (PubMed:25651845).

Plasma; synthesized in the liver.

Thrombophilia due to protein C deficiency, autosomal dominant
Thrombophilia due to protein C deficiency, autosomal recessive

Belongs to the peptidase S1 family.
Contains 2 EGF-like domains.
Contains 1 Gla (gamma-carboxy-glutamate) domain.
Contains 1 peptidase S1 domain.

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.
The 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.

Secreted. Golgi apparatus. Endoplasmic reticulum.