Prothrombin precursor is synthesized in liver as a precursor of prothrombin containing a signal sequence and a propeptide domain at the N-terminus. Before its secretion into plasma, this precursor undergoes several posttranslational modifications, including removal of signal sequence and propeptide domains, glycosylation, and γ-glutamylcarboxylation reaction. Prothrombin, cleaved by the prothrombinase enzyme complex that consists of serine protease factor Xa, cofactor Va, phospholipids and calcium, is converted to thrombin which converts fibrinogen into fibrin which in turn strengthens a protective clot. Activation of prothrombin is crucial in physiological and pathological coagulation. Various rare diseases involving prothrombin(e.g. hypoprothrombinemia) have been described.