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Factor I

Okrój, Marcin LU and Blom, Anna M. LU orcid (2017) p.147-154
Abstract

Factor I (FI) is a serine protease with narrow specificity restricted to activated complement components C3b and C4b. Supported by appropriate cofactors such as factor H or C4b-binding protein, FI cleaves peptide bonds in C3b/C4b after arginyl residues. By doing so it inhibits further propagation of the complement cascade thus contributing to protection from misguided or excessive complement attack on own cells and tissues. Furthermore, inactivated fragments of C3b bind to specific receptors on immune cells and influence their function such as phagocytosis. Production and secretion of FI into bloodstream is mainly supported by liver but extrahepatic sources were also identified, such as keratinocytes, fibroblasts, monocytes and... (More)

Factor I (FI) is a serine protease with narrow specificity restricted to activated complement components C3b and C4b. Supported by appropriate cofactors such as factor H or C4b-binding protein, FI cleaves peptide bonds in C3b/C4b after arginyl residues. By doing so it inhibits further propagation of the complement cascade thus contributing to protection from misguided or excessive complement attack on own cells and tissues. Furthermore, inactivated fragments of C3b bind to specific receptors on immune cells and influence their function such as phagocytosis. Production and secretion of FI into bloodstream is mainly supported by liver but extrahepatic sources were also identified, such as keratinocytes, fibroblasts, monocytes and endothelial cells. Mutations/polymorphism in FI may diminish its secretion or cause loss of function. When leading to complete deficiency, alterations in FI markedly distort the balance between complement activation and inhibition. The outcome is increased rate of bacterial infections and glomerulonephritis. Partial deficiency of FI predisposes to atypical haemolytic uraemic syndrome or age-related macular degeneration.

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author
and
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
Age-related macular degeneration, Atypical haemolytic uraemic syndrome, Complement inhibitor, Complement system, Factor I, Proteolysis, Serine protease
host publication
The Complement FactsBook : Second Edition - Second Edition
pages
8 pages
publisher
Elsevier
external identifiers
  • scopus:85041266259
ISBN
9780128104200
DOI
10.1016/B978-0-12-810420-0.00015-8
language
English
LU publication?
yes
id
ed24e208-eee7-4b6c-9db1-060ab8dba3c9
date added to LUP
2018-02-12 14:26:13
date last changed
2022-05-03 01:21:36
@inbook{ed24e208-eee7-4b6c-9db1-060ab8dba3c9,
  abstract     = {{<p>Factor I (FI) is a serine protease with narrow specificity restricted to activated complement components C3b and C4b. Supported by appropriate cofactors such as factor H or C4b-binding protein, FI cleaves peptide bonds in C3b/C4b after arginyl residues. By doing so it inhibits further propagation of the complement cascade thus contributing to protection from misguided or excessive complement attack on own cells and tissues. Furthermore, inactivated fragments of C3b bind to specific receptors on immune cells and influence their function such as phagocytosis. Production and secretion of FI into bloodstream is mainly supported by liver but extrahepatic sources were also identified, such as keratinocytes, fibroblasts, monocytes and endothelial cells. Mutations/polymorphism in FI may diminish its secretion or cause loss of function. When leading to complete deficiency, alterations in FI markedly distort the balance between complement activation and inhibition. The outcome is increased rate of bacterial infections and glomerulonephritis. Partial deficiency of FI predisposes to atypical haemolytic uraemic syndrome or age-related macular degeneration.</p>}},
  author       = {{Okrój, Marcin and Blom, Anna M.}},
  booktitle    = {{The Complement FactsBook : Second Edition}},
  isbn         = {{9780128104200}},
  keywords     = {{Age-related macular degeneration; Atypical haemolytic uraemic syndrome; Complement inhibitor; Complement system; Factor I; Proteolysis; Serine protease}},
  language     = {{eng}},
  month        = {{10}},
  pages        = {{147--154}},
  publisher    = {{Elsevier}},
  title        = {{Factor I}},
  url          = {{http://dx.doi.org/10.1016/B978-0-12-810420-0.00015-8}},
  doi          = {{10.1016/B978-0-12-810420-0.00015-8}},
  year         = {{2017}},
}