Complement factor B

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Identifiers
Aliases
External IDs	GeneCards: [1]
Orthologs
Species	Human	Mouse
Entrez	n/a	n/a
Ensembl	n/a	n/a
UniProt	n/a	n/a
RefSeq (mRNA)	n/a	n/a
RefSeq (protein)	n/a	n/a
Location (UCSC)	n/a	n/a
PubMed search	n/a	n/a
Wikidata
View/Edit Human

Complement factor B is a protein that in humans is encoded by the CFB gene.

Function

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.

Alternative pathway. (Some labels are in Polish.)

Complement tests

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

Further reading

• Ambrus JL, Peters MG, Fauci AS, Brown EJ (March 1990). "The Ba fragment of complement factor B inhibits human B lymphocyte proliferation". Journal of Immunology. 144 (5): 1549–53. PMID 2307833.
• Bradley DT, Zipfel PF, Hughes AE (June 2011). "Complement in age-related macular degeneration: a focus on function". Eye. 25 (6): 683–93. doi:10.1038/eye.2011.37. PMC 3178140. PMID 21394116.
• Campbell RD (January 1987). "The molecular genetics and polymorphism of C2 and factor B". British Medical Bulletin. 43 (1): 37–49. PMID 3315100.
• Campbell RD, Bentley DR, Morley BJ (September 1984). "The factor B and C2 genes". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 306 (1129): 367–78. doi:10.1098/rstb.1984.0097. PMID 6149579.
• Yu CY (1999). "Molecular genetics of the human MHC complement gene cluster". Experimental and Clinical Immunogenetics. 15 (4): 213–30. doi:10.1159/000019075. PMID 10072631.
• Rawal N, Pangburn MK (March 2001). "Structure/function of C5 convertases of complement". International Immunopharmacology. 1 (3): 415–22. doi:10.1016/S1567-5769(00)00039-4. PMID 11367526.
• Arnason A, Larsen B, Marshall WH, Edwards JH, Macintosh P, Olaisen B, Teisberg P (August 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 (October 1992). "Production and interferon-gamma-mediated regulation of complement component C2 and factors B and D by the astroglioma cell line U105-MG". The Biochemical Journal. 287. 287 ( Pt 2): 595–601. PMC 1133207. PMID 1445220.
• Yancey KB, Overholser O, Domloge-Hultsch N, Li LJ, Caughman SW, Bisalbutra P (March 1992). "Human keratinocytes and A-431 cells synthesize and secrete factor B, the major zymogen protease of the alternative complement pathway". The Journal of Investigative Dermatology. 98 (3): 379–83. doi:10.1111/1523-1747.ep12499812. PMID 1545147.
• Niemann MA, Bhown AS, Miller EJ (March 1991). "The principal site of glycation of human complement factor B". The Biochemical Journal. 274. 274 ( Pt 2): 473–80. PMC 1150163. PMID 2006911.
• Davrinche C, Abbal M, Clerc A (1991). "Molecular characterization of human complement factor B subtypes". Immunogenetics. 32 (5): 309–12. doi:10.1007/bf00211644. PMID 2249879.
• Farries TC, Lachmann PJ, Harrison RA (August 1988). "Analysis of the interaction between properdin and factor B, components of the alternative-pathway C3 convertase of complement". The Biochemical Journal. 253 (3): 667–75. PMC 1149358. PMID 3140783.
• Wu LC, Morley BJ, Campbell RD (January 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 (July 1983). "Molecular cloning and characterization of the gene coding for human complement protein factor B". Proceedings of the National Academy of Sciences of the United States of America. 80 (14): 4464–8. doi:10.1073/pnas.80.14.4464. PMC 384059. PMID 6308626.
• Morley BJ, Campbell RD (January 1984). "Internal homologies of the Ba fragment from human complement component Factor B, a class III MHC antigen". The EMBO Journal. 3 (1): 153–7. PMC 557312. PMID 6323161.
• Christie DL, Gagnon J (January 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". The Biochemical Journal. 209 (1): 61–70. PMC 1154056. PMID 6342610.
• Mole JE, Anderson JK, Davison EA, Woods DE (March 1984). "Complete primary structure for the zymogen of human complement factor B". The Journal of Biological Chemistry. 259 (6): 3407–12. PMID 6546754.
• Woods DE, Markham AF, Ricker AT, Goldberger G, Colten HR (September 1982). "Isolation of cDNA clones for the human complement protein factor B, a class III major histocompatibility complex gene product". Proceedings of the National Academy of Sciences of the United States of America. 79 (18): 5661–5. doi:10.1073/pnas.79.18.5661. PMC 346964. PMID 6957884.
• Maruyama K, Sugano S (January 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 (January 1994). "Human factor B. Complete cDNA sequence of the BF*S allele". Human Immunology. 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
• Complement+Factor+B at the US National Library of Medicine Medical Subject Headings (MeSH)