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Factor Xii Information

Coagulation factor XII also known as Hageman factor is a plasma protein. It is the zymogen form of factor XIIa, an enzyme (EC 3.4.21.38) of the serine protease (or serine endopeptidase) class. In humans, factor XII is encoded by the F12 gene.[1]

Contents

Function

Factor XII is part of the coagulation cascade and activates factor XI and prekallikrein. Factor XII itself is activated to factor XIIa by negatively charged surfaces, such as glass.[2]

The coagulation cascade.

In vivo, factor XII is activated by contact to polyanions. Activated platelets secrete inorganic polymers, polyphosphates. Contact to polyphosphates activates factor XII and initiates fibrin formation by the intrinsic pathway of coagulation with critical importance for thrombus formation.Targeting polyphosphates with phosphatases interfered with procoagulant activity of activated platelets and blocked platelet-induced thrombosis in mice. Addition of polyphosphates restored defective plasma clotting of Hermansky-Pudlak syndrome patients, indicating that the inorganic polymer is the endogenous factor XII activator in vivo. Platelet polyphosphate-driven factor XII activation provides the link from primary hemostasis (formation of a platelet plug) with secondary hemostasis (fibrin meshwork formation).[3]

Genetics

The gene for factor XII is located on the tip of the long arm of the fifth chromosome (5q33-qter).[1]

Role in disease

No significant role in disease. Factor XII does not contribute to bleeding

History

Hageman factor was first discovered in 1955 when a routine preoperative blood sample of the 37-year-old railroad brakeman John Hageman was found to have prolonged clotting time in test tubes, even though he had no hemorrhagic symptoms. Hageman was then examined by Dr. Oscar Ratnoff who found that Mr. Hageman lacked a previously unidentified clotting factor.[4] Dr. Ratnoff later found that the Hageman factor deficiency is an autosomal recessive disorder, when examining several related people who had the deficiency. Paradoxically, pulmonary embolism contributed to Hageman's death after an occupational accident. Since then, case series clinical studies have identified an association of thrombosis and Factor XII deficiency, though the pathophysiology of the relationship is unclear. Hepatocytes express blood coagulation factor XII.[5]

References

  1. ^ a b Cool DE, MacGillivray RT (October 1987). "Characterization of the human blood coagulation factor XII gene. Intron/exon gene organization and analysis of the 5'-flanking region". J. Biol. Chem. 262 (28): 13662–73. PMID 2888762. http://www.jbc.org/cgi/reprint/262/28/13662.
  2. ^ Encyclopedia Britannica Online, accessed 28/7/08
  3. ^ Müller F, Mutch, NJ, Schenk WA, Smith SA, Esterl L, Spronk HM, Schmidbauer S, Gahl WA, Morrissey JH, Renné T (Dec 2009). "Platelet polyphosphates are proinflammatory and procoagulant mediators in vivo.". CELL 139 (6): 1143–56. doi:10.1016/j.cell.2009.11.001. PMID 20005807.
  4. ^ Ratnoff OD, Margolius A (1955). "Hageman trait: an asymptomatic disorder of blood coagulation". Trans. Assoc. Am. Physicians 68: 149–54. PMID 13299324.
  5. ^ Gordon EM, Gallagher CA, Johnson TR, Blossey BK, Ilan J (April 1990). "Hepatocytes express blood coagulation factor XII (Hageman factor)". J. Lab. Clin. Med. 115 (4): 463–9. PMID 2324612.

Further reading

External links

· · Proteins: coagulation
Coagulation factors
Primary hemostasis

vWF

platelet membrane glycoproteins: Ib (A, B, IX) · IIb/IIIa (IIb, IIIa) · VI
Intrinsic pathway HMWK/Bradykinin · Prekallikrein/Kallikrein · XII "Hageman" XI · IX · VIII
Extrinsic pathway III "Tissue factor" · VII
Common pathway X · V · II "(Pro)thrombin" · I "Fibrin" · Fibrinogen (FGA, FGG) XIII
Coagulation inhibitors Antithrombin (inhibits II, IX, X, XI, XII) · Protein C (inhibits V, VIII)/Protein S (cofactor for protein C) · Protein Z (inhibits X) · ZPI (inhibits X, XI) · TFPI (inhibits III)
Thrombolysis/fibrinolysis Plasmin · tPA/urokinase · PAI-1/2 · α2-AP · α2-macroglobulin · TAFI

: MYL

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· · Endopeptidases: serine proteases/serine endopeptidases (EC 3.4.21)
Digestive enzymes Enteropeptidase · Trypsin · Chymotrypsin · Elastase (Neutrophil, Pancreatic)
Coagulation factors: Thrombin · Factor VIIa · Factor IXa · Factor Xa · Factor XIa · Factor XIIa · Kallikrein (PSA, KLK1, KLK2, KLK3, KLK4, KLK5, KLK6, KLK7, KLK8, KLK9, KLK10, KLK11, KLK12, KLK13, KLK14, KLK15) fibrinolysis: Plasmin · Plasminogen activator (Tissue plasminogen activator · Urinary plasminogen activator)
Complement system Factor B · Factor D · Factor I · MASP (MASP1, MASP2) · C3-convertase
Other immune system Chymase · Granzyme · Tryptase · Proteinase 3/Myeloblastin
Venombin Ancrod · Batroxobin
Other Acrosin · Prolyl endopeptidase · Pronase · Proprotein convertases (1, 2) · Reelin · Subtilisin/Furin · Streptokinase · S1P · Cathepsin (A, G)
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Categories: Human proteins | Coagulation system | EC 3.4.21

 

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