Proaccelerin

Proaccelerin, also known as Factor V, is a protein produced in the liver that plays a crucial role in blood coagulation. It is a zymogen, meaning it is an inactive precursor that must be activated to perform its function. Activation of proaccelerin occurs through its cleavage by thrombin, a key enzyme in the coagulation cascade. Once activated, Factor V becomes a cofactor, working in conjunction with Factor Xa to convert prothrombin into thrombin. This amplification step is essential for the rapid and efficient formation of a fibrin clot, which is necessary to stop bleeding.

Proaccelerin is a large glycoprotein composed of four domains. Its synthesis is regulated by various factors, and its levels in the blood can be affected by certain medical conditions. Genetic deficiencies in proaccelerin are rare but can lead to a bleeding disorder known as Factor V deficiency, characterized by an increased tendency to bruise and bleed. Conversely, certain mutations in the gene encoding proaccelerin can lead to an increased risk of thrombosis, or blood clotting, a condition known as Factor V Leiden. This mutation makes activated Factor V more resistant to inactivation by protein C, a natural anticoagulant. Research continues to explore the complex regulatory mechanisms of proaccelerin and its implications in hemostasis and thrombotic disorders.