Sample: Fresh Citrated plasma (store frozen)
Range: 70 - 140
Remarks: Protein C is a Vitamin K-dependent plasma protein that is synthesized by the liver as an inactive precursor. It is then further transformed into activated PC by a complex of thrombin and the endothelia factor, thrombomodulin that is bound to phospholipid membrane in a calcium-dependant manner. Activated Protein C regulates the coagulation process by inactivating factors Va and VIIIa. Protein S, another vitamin K-dependent protein, serves as an essential cofactor of activated Prptein C for the inactivation of factors Va and VIIIa. In inhibiting these factors, Protein C serves to limit thrombus extension, and thus acts as a major regulator of the coagulation process.