F12
Function
Factor XII is a serum glycoprotein that participates in the initiation of blood coagulation, fibrinolysis, and the generation of bradykinin and angiotensin. Prekallikrein is cleaved by factor XII to form kallikrein, which then cleaves factor XII first to alpha-factor XIIa and then trypsin cleaves it to beta-factor XIIa. Alpha-factor XIIa activates factor XI to factor XIa (PubMed:2019570, PubMed:21304106, PubMed:8427954).
Involvement in disease
Factor XII deficiency
FA12D
An asymptomatic anomaly of in vitro blood coagulation. Its diagnosis is based on finding a low plasma activity of the factor in coagulating assays. It is usually only accidentally discovered through pre-operative blood tests. Factor XII deficiency is divided into two categories, a cross-reacting material (CRM)-negative group (negative F12 antigen detection) and a CRM-positive group (positive F12 antigen detection).
None
The disease is caused by variants affecting the gene represented in this entry.
Angioedema, hereditary, 3
HAE3
A hereditary angioedema occurring only in women. Hereditary angioedema is an autosomal dominant disorder characterized by episodic local swelling involving subcutaneous or submucous tissue of the upper respiratory and gastrointestinal tracts, face, extremities, and genitalia. Hereditary angioedema type 3 differs from types 1 and 2 in that both concentration and function of C1 esterase inhibitor are normal. Hereditary angioedema type 3 is precipitated or worsened by high estrogen levels (e.g., during pregnancy or treatment with oral contraceptives).
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
Factor XII is activated by kallikrein in alpha-factor XIIa, which is further converted by trypsin into beta-factor XIIa. Alpha-factor XIIa is composed of an NH2-terminal heavy chain, called coagulation factor XIIa heavy chain, and a COOH-terminal light chain, called coagulation factor XIIa light chain, connected by a disulfide bond. Beta-factor XIIa is composed of 2 chains linked by a disulfide bond, an N-terminal nonapeptide, called beta-factor XIIa part 1, and coagulation factor XIIa light chain, also known in this context as beta-factor XIIa part 2.
O- and N-glycosylated. The O-linked polysaccharides were not identified, but are probably the mucin type linked to GalNAc.
Sequence Similarities
Belongs to the peptidase S1 family.
Cellular localization
- Secreted
Alternative names
Coagulation factor XII, Hageman factor, HAF, F12