Protein C

Protein C is an inactive enzyme form (zymogen) of activated protein C (APC) which plays an important role in anticoagulation. Protein C is a vitamin K dependent protein produced by the liver. Protein C is activated by thrombin, with Protein S as a cofactor, to from APC, a serine protease. APC then acts to inhibit the activation of Factor V and VIII. Protein C deficiency ranges from mild to severe. Depending on the type of deficiency (heterozygous or homozygous), it can lead to an increased risk of thrombosis.