Prekallikrein
Prekallikrein (PK), also known as Fletcher factor, is an 85,000 Mr
Structure
Prekallikrein is homologous to factor XI, and similarly consists of four apple domains and a fifth, catalytic serine protease domain. The four apple domains create a disk-like platform around the base of the catalytic domain. However, unlike factor XI, prekallikrein does not form dimers.
Prekallikrein is activated to form kallikrein by factor XII cleavage of a bond homologous to the corresponding bond cleaved during factor XI activation.[2]
Prekallikrein deficiency
Hereditary deficiencies in PK are very rare. They can cause a prolonged
Deficiencies in PK can also be acquired due to some disease states, such as
Although most cases of prekallikrein deficiency are asymptomatic, a few reports link severe prekallikrein deficiency with thrombotic phenomena and recurrent pregnancy loss. More recently, a case of prekallikrein deficiency was shown to be associated with severe mucosal bleeding.[3]
Discovery of prekallikrein
PK was initially described by Hathaway et al. in 1965 after encountering a Kentucky family who exhibited strikingly abnormal APTT results, but showed no bleeding symptoms. The family appeared to have a hereditary deficiency in an unknown coagulation factor, dubbed “Fletcher factor” after the family. In 1973 Kirk Wuepper determined that Fletcher factor and prekallikrein were the same.[4]
References
- ^ ISBN 978-0071348348.
- PMID 17922805.
- PMID 19773642.
- ^ Online Mendelian Inheritance in Man (OMIM): KALLIKREIN B, PLASMA, 1; KLKB1 - 229000