Protein C and protein S are anticoagulant proteins that, together with thrombomodulin and thrombin, form a complex on endothelial cells that proteolytically inactivates coagulation factors Va and VIIIa — cofactors of the common and intrinsic coagulation pathways respectively — thereby limiting fibrin generation and restraining clot propagation during secondary hemostasis. Deficiency of either protein (hereditary, autosomal dominant, and further classified as quantitative Type 1 or qualitative Type 2, or acquired via impaired hepatic synthesis, vitamin K antagonist therapy, or excessive urinary loss) removes this inhibitory brake on factors Va/VIIIa, producing a hypercoagulable state with increased venous thromboembolism risk; this belongs to hematology, within the physiology and pathophysiology of hemostasis and coagulation regulation.
Protein C and protein S are anticoagulant proteins that, together with thrombomodulin and thrombin, form a complex on endothelial cells that proteolytically inactivates coagulation factors Va and VII…