Vitamin K-dependent coagulation factors (Factors II, VII, IX, X) and regulatory proteins (Protein C, Protein S) (None universally accepted for the entire group; individually: FII (prothrombin), FVII, FIX, FX, PC (Protein C), PS (Protein S))

Vitamin K-dependent coagulation factors refer to a group of plasma proteins—specifically Factors II (prothrombin), VII, IX, X, Protein C, and Protein S—that require γ-carboxylation by a vitamin K-dependent enzyme to function properly in blood coagulation and anticoagulation pathways. Factors II, VII, IX, and X are serine proteases that drive the formation of fibrin clots, while Protein C (a serine protease zymogen) and Protein S (a non-enzymatic cofactor) function together to physiologically inhibit excess coagulation by degrading activated cofactors Va and VIIIa. Genetic or acquired deficiency in these factors can produce either bleeding or thrombotic disorders. Therapeutically, these proteins are central targets for both anticoagulant (e.g., warfarin) and replacement therapies (e.g., prothrombin complex concentrate). Note: The grouping "Coagulation Factors II, VII, IX, X and Proteins C & S" is used clinically (e.g., in prothrombin complex concentrates), but each protein is a unique entity and is best described individually for molecular targeting, genetic studies, and most research purposes.

Other names

Vitamin K-dependent clotting factorsProthrombin complex componentsVK-dependent factorsPCC factors (in the context of prothrombin complex concentrates)Specific factor names: Prothrombin (FII)Factor VIIFactor IXFactor XProtein CProtein S

Inhibition: Vitamin K antagonists prevent activation via impaired γ-carboxylation Replacement: Prothrombin complex concentrates replenish depleted factors Inhibition of active enzymes: Direct (DOACs) or indirect (heparin) enzyme inactivation Activated Protein C: Inactivation of cofactors Va and VIIIa, anticoagulant action Protein S: Cofactor for Protein C-mediated inactivation