Complement factor B

Complement factor B
PDB rendering based on 1dle.
Available structures PDB 1DLE, 1Q0P, 1RRK, 1RS0, 1RTK, 2OK5, 2WIN, 3HRZ, 3HS0
Identifiers
Symbols	CFB; AHUS4; BF; BFD; CFAB; FB; FBI12; FLJ54899; GBG; H2-Bf; PBF2
External IDs	OMIM: 138470 MGI: 105975 HomoloGene: 1292 GeneCards: CFB Gene
EC number	3.4.21.47
Gene Ontology Molecular function • complement binding • serine-type endopeptidase activity • peptidase activity Cellular component • extracellular region • extracellular region • plasma membrane • plasma membrane Biological process • proteolysis • complement activation • complement activation, alternative pathway • complement activation, alternative pathway • innate immune response Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	629	14962
Ensembl	ENSG00000166285	ENSMUSG00000090231
UniProt	P00751	Q3U925
RefSeq (mRNA)	NM_001710.5	NM_008198
RefSeq (protein)	NP_001701.2	NP_032224
Location (UCSC)	Chr c6_COX: 32.05 – 32.05 Mb	Chr 17: 34.99 – 35 Mb
PubMed search	[1]	[2]

Alternative pathway. (Some labels are in Polish.)

Complement factor B is a protein that in humans is encoded by the CFB gene.^[1]

This gene encodes complement factor B, a component of the alternative pathway of complement activation. Factor B circulates in the blood as a single chain polypeptide. Upon activation of the alternative pathway, it is cleaved by complement factor D yielding the noncatalytic chain Ba and the catalytic subunit Bb. The active subunit Bb is a serine protease that associates with C3b to form the alternative pathway C3 convertase. Bb is involved in the proliferation of preactivated B lymphocytes, while Ba inhibits their proliferation. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. This cluster includes several genes involved in regulation of the immune reaction. The polyadenylation site of this gene is 421 bp from the 5' end of the gene for complement component 2.^[1]

Complement tests

C4 (C)	FB (A)	C3	CH50	Conditions
·	↓	↓	↓	PSG, C3 NeF AA
↓	·	↓	·	HA, C4D
·	·	·	↓	TCPD
↓	· /↓	↓	↓	SLE
↑	↑	↑	↑	inflammation

References

1. ^ ^{a b} "Entrez Gene: CFB complement factor B". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=629. 

Further reading

• Bradley, D T; Zipfel, P F; Hughes, A E (2011). "Complement in age-related macular degeneration: a focus on function". Eye 25 (6). doi:10.1038/eye.2011.37. PMID 21394116. 
• Campbell RD (1988). "The molecular genetics and polymorphism of C2 and factor B". Br. Med. Bull. 43 (1): 37–49. PMID 3315100. 
• Campbell RD, Bentley DR, Morley BJ (1984). "The factor B and C2 genes". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 306 (1129): 367–78. doi:10.1098/rstb.1984.0097. PMID 6149579. 
• Yu CY (1999). "Molecular genetics of the human MHC complement gene cluster". Exp. Clin. Immunogenet. 15 (4): 213–30. doi:10.1159/000019075. PMID 10072631. 
• Rawal N, Pangburn MK (2001). "Structure/function of C5 convertases of complement". Int. Immunopharmacol. 1 (3): 415–22. doi:10.1016/S1567-5769(00)00039-4. PMID 11367526. 
• Arnason A, Larsen B, Marshall WH, et al. (1977). "Very close linkage between HLA-B and Bf inferred from allelic association". Nature 268 (5620): 527–8. doi:10.1038/268527a0. PMID 889587. 
• Barnum SR, Ishii Y, Agrawal A, Volanakis JE (1992). "Production and interferon-gamma-mediated regulation of complement component C2 and factors B and D by the astroglioma cell line U105-MG". Biochem. J.. 287 ( Pt 2): 595–601. PMC 1133207. PMID 1445220. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1133207. 
• Yancey KB, Overholser O, Domloge-Hultsch N, et al. (1992). "Human keratinocytes and A-431 cells synthesize and secrete factor B, the major zymogen protease of the alternative complement pathway". J. Invest. Dermatol. 98 (3): 379–83. doi:10.1111/1523-1747.ep12499812. PMID 1545147. 
• Niemann MA, Bhown AS, Miller EJ (1991). "The principal site of glycation of human complement factor B". Biochem. J.. 274 ( Pt 2): 473–80. PMC 1150163. PMID 2006911. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1150163. 
• Davrinche C, Abbal M, Clerc A (1991). "Molecular characterization of human complement factor B subtypes". Immunogenetics 32 (5): 309–12. PMID 2249879. 
• Farries TC, Lachmann PJ, Harrison RA (1988). "Analysis of the interaction between properdin and factor B, components of the alternative-pathway C3 convertase of complement". Biochem. J. 253 (3): 667–75. PMC 1149358. PMID 3140783. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1149358. 
• Wu LC, Morley BJ, Campbell RD (1987). "Cell-specific expression of the human complement protein factor B gene: evidence for the role of two distinct 5'-flanking elements". Cell 48 (2): 331–42. doi:10.1016/0092-8674(87)90436-3. PMID 3643061. 
• Campbell RD, Porter RR (1983). "Molecular cloning and characterization of the gene coding for human complement protein factor B". Proc. Natl. Acad. Sci. U.S.A. 80 (14): 4464–8. doi:10.1073/pnas.80.14.4464. PMC 384059. PMID 6308626. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=384059. 
• Morley BJ, Campbell RD (1984). "Internal homologies of the Ba fragment from human complement component Factor B, a class III MHC antigen". EMBO J. 3 (1): 153–7. PMC 557312. PMID 6323161. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=557312. 
• Christie DL, Gagnon J (1983). "Amino acid sequence of the Bb fragment from complement Factor B. Sequence of the major cyanogen bromide-cleavage peptide (CB-II) and completion of the sequence of the Bb fragment". Biochem. J. 209 (1): 61–70. PMC 1154056. PMID 6342610. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1154056. 
• Mole JE, Anderson JK, Davison EA, Woods DE (1984). "Complete primary structure for the zymogen of human complement factor B". J. Biol. Chem. 259 (6): 3407–12. PMID 6546754. 
• Woods DE, Markham AF, Ricker AT, et al. (1982). "Isolation of cDNA clones for the human complement protein factor B, a class III major histocompatibility complex gene product". Proc. Natl. Acad. Sci. U.S.A. 79 (18): 5661–5. doi:10.1073/pnas.79.18.5661. PMC 346964. PMID 6957884. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=346964. 
• Maruyama K, Sugano S (1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides". Gene 138 (1–2): 171–4. doi:10.1016/0378-1119(94)90802-8. PMID 8125298. 
• Mejía JE, Jahn I, de la Salle H, Hauptmann G (1994). "Human factor B. Complete cDNA sequence of the BF*S allele". Hum. Immunol. 39 (1): 49–53. doi:10.1016/0198-8859(94)90100-7. PMID 8181962. 

External links

• GeneReviews/NCBI/NIH/UW entry on Atypical Hemolytic-Uremic Syndrome
• OMIM entries on Atypical Hemolytic-Uremic Syndrome
• The MEROPS online database for peptidases and their inhibitors: S01.196
• MeSH Complement+Factor+B

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