Factor H is a member of the regulators of complement activation family and is a complement control protein. It is a large (155 kilodalton), soluble glycoprotein that circulates in human plasma (at a concentration of 500-800 micrograms per mL). Its main job is to regulate the Alternative Pathway of the complement system, ensuring that the complement system is directed towards pathogens and does not damage host tissue. Factor H regulates complement activation on self cells by possessing both cofactor activity for Factor I mediated C3b cleavage, and decay accelerating activity against the alternative pathway C3 convertase, C3bBb. Factor H protects self cells from complement activation but not bacteria/viruses, in that it binds to glycosaminoglycans (GAGs) that are present on host cells but not pathogen cell surfaces.
Sources
Pangburn, M.K. Host recognition and target differentiation by factor H, a regulator of the alternative pathway of complement. Immunopharmacology 49, 149-57 (2000).
Aslam M. & Perkins S.J. Folded-back solution structure of monomeric factor H of human complement by synchrotron X-ray and neutron scattering, analytical ultracentrifugation and constrained molecular modelling. J Mol Biol. 309(5), 1117-38 (2001).
Kirkitadze, M.D. & Barlow, P.N. Structure and flexibility of the multiple domain proteins that regulate complement activation. Immunol Rev 180, 146-61 (2001).
Hageman, G.S. et al. A common haplotype in the complement regulatory gene factor H (HF1/CFH) predisposes individuals to age-related macular degeneration. Proc Natl Acad Sci U S A 102, 7227-32. (2005).
Kardys, I. et al. A common polymorphism in the complement factor h gene is associated with increased risk of myocardial infarction the rotterdam study. J Am Coll Cardiol. 47, 1568-75. (2006).
Herbert, A.P. et al. Structure shows that a glycosaminoglycan and protein recognition site in factor H is perturbed by age-related macular degeneration-linked single nucleotide polymorphism. J Biol Chem. 282(26), 18960-8. (2007).
Aslam M. & Perkins S.J. Folded-back solution structure of monomeric factor H of human complement by synchrotron X-ray and neutron scattering, analytical ultracentrifugation and constrained molecular modelling. J Mol Biol. 309(5), 1117-38 (2001).
Kirkitadze, M.D. & Barlow, P.N. Structure and flexibility of the multiple domain proteins that regulate complement activation. Immunol Rev 180, 146-61 (2001).
Hageman, G.S. et al. A common haplotype in the complement regulatory gene factor H (HF1/CFH) predisposes individuals to age-related macular degeneration. Proc Natl Acad Sci U S A 102, 7227-32. (2005).
Kardys, I. et al. A common polymorphism in the complement factor h gene is associated with increased risk of myocardial infarction the rotterdam study. J Am Coll Cardiol. 47, 1568-75. (2006).
Herbert, A.P. et al. Structure shows that a glycosaminoglycan and protein recognition site in factor H is perturbed by age-related macular degeneration-linked single nucleotide polymorphism. J Biol Chem. 282(26), 18960-8. (2007).
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