<unk> <unk>  is an essential blood-clotting protein, also known as anti-hemophilic factor (AHF). In humans,<unk>  is encoded by the<unk>  gene. Defects in this gene result in hemophilia A, a recessive X-linked coagulation disorder.<unk>  is produced in liver sinusoidal cells and endothelial cells outside the liver throughout the body. This protein circulates in the bloodstream in an inactive form, bound to another molecule called von Willebrand factor, until an injury that damages blood vessels occurs. In response to injury, coagulation<unk>  is activated and separates from von Willebrand factor. The active protein (sometimes written as coagulation<unk> a) interacts with another coagulation factor called factor IX. This interaction sets off a chain of additional chemical reactions that form a blood clot.<unk>  participates in blood coagulation; it is a cofactor for factor IXa, which, in the presence of Ca2+ and phospholipids, forms a complex that converts factor X to the activated form Xa. The<unk>  gene produces two alternatively spliced transcripts. Transcript variant 1 encodes a large glycoprotein, isoform a, which circulates in plasma and associates with von Willebrand factor in a noncovalent complex. This protein undergoes multiple cleavage events. Transcript variant 2 encodes a putative small protein, isoform b, which consists primarily of the phospholipid binding domain of<unk> c. This binding domain is essential for coagulant activity. People with high levels of<unk>  are at increased risk for deep vein thrombosis and pulmonary embolism. Copper is a required cofactor for<unk>  and copper deficiency is known to increase the activity of<unk> . There is a formulation as a medication that is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.
Factor VIII
Factor IX
Factor XI
Thrombin
Prothrombinase
Von Willebrand factor
Fibrinogen
Platelet-activating factor