2qfg: Difference between revisions
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==Overview== | ==Overview== | ||
Factor H (FH) is a plasma glycoprotein that plays a central role in | Factor H (FH) is a plasma glycoprotein that plays a central role in regulation of the alternative pathway of complement. It is composed of 20 short complement regulator (SCR) domains. The SCR-1/5 fragment is required for decay acceleration and cofactor activity, while the SCR-16/20 fragment possesses binding sites for complement C3d and heparin. X-ray scattering and analytical ultracentrifugation showed that SCR-1/5 was monomeric, while SCR-16/20 formed dimers. The Guinier radius of gyration R(G) of 4.3 nm for SCR-1/5 and those of 4.7 nm and about 7.8 nm for monomeric and dimeric SCR-16/20, respectively, showed that their structures are partially folded back and bent. The distance distribution function P(r) showed that SCR-1/5 has a maximum dimension of 15 nm while monomeric and dimeric SCR-16/20 are 17 nm and about 27 nm long, respectively. The sedimentation coefficient of 2.4 S for SCR-1/5 showed no concentration-dependence, while that for SCR-16/20 was 2.8 S for the monomer and 3.9 S for the dimer. Sedimentation equilibrium data showed that SCR-1/5 is monomeric while SCR-16/20 exhibited a weak monomer-dimer equilibrium with a dissociation constant of 16 microM. The constrained scattering and sedimentation modelling of SCR-1/5 and SCR-16/20 showed that partially folded-back and bent flexible SCR arrangements fitted both data sets better than extended linear arrangements, and that the dimer was best modelled in the SCR-16/20 model by an end-to-end association of two SCR-20 domains. The SCR-1/5 and SCR-16/20 models were conformationally similar to the previously determined partially folded-back structure for intact wild-type FH, hence suggesting a partial explanation of the intact FH structure. Comparison of the SCR-16/20 model with the crystal structure of C3b clarified reasons for the distribution of mutations leading to atypical haemolytic uraemic syndrome. | ||
==Disease== | |||
Known diseases associated with this structure: Complement factor H deficiency OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=134370 134370]], Factor H and factor H-like 1 OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=134370 134370]], Hemolytic-uremic syndrome OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=134370 134370]], Macular degeneration, age-related, 4 OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=134370 134370]], Membranoproliferative glomerulonephritis with CFH deficiency OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=134370 134370]] | |||
==About this Structure== | ==About this Structure== | ||
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[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Gilbert, H | [[Category: Gilbert, H E.]] | ||
[[Category: Gordon, D | [[Category: Gordon, D L.]] | ||
[[Category: Griggs, K | [[Category: Griggs, K M.]] | ||
[[Category: Okemefuna, A | [[Category: Okemefuna, A I.]] | ||
[[Category: Ormsby, R | [[Category: Ormsby, R J.]] | ||
[[Category: Perkins, S | [[Category: Perkins, S J.]] | ||
[[Category: age-related macular degeneration]] | [[Category: age-related macular degeneration]] | ||
[[Category: alternative splicing]] | [[Category: alternative splicing]] | ||
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[[Category: x-ray scattering]] | [[Category: x-ray scattering]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:38:57 2008'' | ||