Factor IX is a vitamin K-dependent plasma protein that participates in the intrinsic pathway of blood coagulation by converting factor X to its active form in the presence of Ca(2+) ions, phospholipids, and factor VIIIa. Defects in F9 are the cause of recessive X-linked hemophilia B (HEMB); also known as Christmas disease. Mutations in position 43 (Oxford-3, San Dimas) and 46 (Cambridge) prevents cleavage of the propeptide, mutation in position 93 (Alabama) probably fails to bind to cell membranes, mutation in position 191 (Chapel-Hill) or in position 226 (Nagoya OR Hilo) prevent cleavage of the activation peptide. Defects in F9 are the cause of thrombophilia due to factor IX defect (THPH8). A hemostatic disorder characterized by a tendency to thrombosis. Belongs to the peptidase S1 family. Note: This description may include information from UniProtKB.
Protein type: EC 220.127.116.11; Protease; Secreted; Secreted, signal peptide