Factor I (Fibrinogen) is a soluble plasma glycoprotein, synthesised by the liver, that is converted by thrombin into fibrin during blood coagulation. This is achieved through processes in the coagulation cascade that activate the zymogen prothrombin to the serine protease thrombin, which is responsible for converting fibrinogen into fibrin. Synonyms: Monoclonal Factor I antibody, Anti-Factor I antibody, Factor-I antibody, Fibrinogen antibody.