The F5 gene encodes coagulation factor V, which is an essential cofactor of the blood coagulation cascade. Factor V is primarily synthesized in the liver and it's inactive form circulates in plasma until the coagulation system is activated by an injury that damages blood vessels. When converted into the active form (called factor Va), it interacts with activated coagulation factor X (factor Xa) to convert prothrombin to thrombin. Thrombin then converts fibrinogen into fibrin, which forms a mesh by binding together and stabilizes the platelet plug at the injury site. Coagulation factor V also has another role in regulating the coagulation system through its interaction with activated protein C (APC). APC normally inactivates coagulation factor V by cleaving it at specific sites. This inactivation slows down the clotting process and prevents the development of an abnormal blood clot. When coagulation factor V is cleaved at a particular site (protein position 506), it can work with APC to inactivate factor VIIIa, which is another protein that is essential for normal blood clotting.