Complement factor B

CFB
Identifiers
Aliases	CFB, Cfb, AI195813, AI255840, Bf, C2, Fb, H2-Bf, AHUS4, ARMD14, BFD, CFAB, CFBD, FBI12, GBG, PBF2, complement factor B
External IDs	OMIM: 138470; MGI: 105975; GeneCards: CFB
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	3HS0, 1DLE, 1Q0P, 1RRK, 1RS0, 1RTK, 2OK5, 2WIN, 2XWB, 2XWJ, 3HRZ
Enzyme activity
Gene location (Human)
Chr.	Chromosome 6 (human)
End	31,952,084 bp
Gene location (Mouse)
Chr.	Chromosome 17 (mouse)
End	35,081,494 bp
RNA expression pattern
	Top expressed in
	right lobe of liver; ; gallbladder; ; appendix; ; duodenum; ; islet of Langerhans; ; olfactory zone of nasal mucosa; ; Descending thoracic aorta; ; gastric mucosa; ; right coronary artery; ; human kidney;
	Top expressed in
	proximal tubule; ; right kidney; ; human kidney; ; white adipose tissue; ; hepatobiliary system; ; liver; ; jejunum; ; ileum; ; colon; ; duodenum;
	More reference expression data
	; ;
	More reference expression data
Gene ontology
Molecular function	peptidase activity; serine-type peptidase activity; serine-type endopeptidase activity; hydrolase activity; complement binding; protein binding;
Cellular component	extracellular region; plasma membrane; blood microparticle; extracellular exosome; extracellular space;
Biological process	complement activation; regulation of complement activation; proteolysis; immune system process; complement activation, alternative pathway; innate immune response;
	Sources:Amigo / QuickGO
Orthologs
Databases	NCBI: entry; OMA: entry
	629
	14962
ENSG00000243570; ENSG00000239754; ENSG00000243649; ENSG00000241253; ENSG00000242335;
	ENSG00000241534; ENSG00000204359
	ENSMUSG00000090231
	P00751
	P04186
	NM_001710
	NM_001142706; NM_008198
	NP_001701
	NP_001136178; NP_032224; NP_001389804
	Wikidata
View/Edit Human	View/Edit Mouse

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. It is directly paralogous to complement component 2 (C2) of the classical pathway, occupying the same locus on Chromosome 6 (6p21.33) and sharing 39% sequence homology, with even greater functional homology due to conservative amino acid replacements accounting for 11% of the divergence. Both are serine proteases with directly analogous functions in their respective complement activation pathways.

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 harbors the serine protease domain 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.

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

References

1 2 3 ENSG00000239754, ENSG00000243649, ENSG00000241253, ENSG00000242335, ENSG00000241534, ENSG00000204359 GRCh38: Ensembl release 89: ENSG00000243570, ENSG00000239754, ENSG00000243649, ENSG00000241253, ENSG00000242335, ENSG00000241534, ENSG00000204359 – Ensembl, May 2017
1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000090231 – Ensembl, May 2017
↑ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
↑ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
1 2 "Entrez Gene: CFB complement factor B".
1 2 Bentley DR, Campbell RD (1986). "C2 and factor B: structure and genetics". Biochemical Society Symposium. 51: 7–18. PMID 3101701.

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). Baltimore: 1549–1553. doi:10.4049/jimmunol.144.5.1549. PMID 2307833.
Bradley DT, Zipfel PF, Hughes AE (June 2011). "Complement in age-related macular degeneration: a focus on function". Eye. 25 (6). London, England: 683–693. 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. doi:10.1093/oxfordjournals.bmb.a072175. 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): 367–378. Bibcode:1984RSPTB.306..367C. 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): 213–230. doi:10.1159/000019075. PMID 10072631. S2CID 25061446.
Rawal N, Pangburn MK (March 2001). "Structure/function of C5 convertases of complement". International Immunopharmacology. 1 (3): 415–422. doi:10.1016/S1567-5769(00)00039-4. PMID 11367526.
Arnason A, Larsen B, Marshall WH, Edwards JH, Macintosh P, Olaisen B, et al. (August 1977). "Very close linkage between HLA-B and Bf inferred from allelic association". Nature. 268 (5620): 527–528. Bibcode:1977Natur.268..527A. doi:10.1038/268527a0. PMID 889587. S2CID 4262433.
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. doi:10.1042/bj2870595. 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): 379–383. 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): 473–480. doi:10.1042/bj2740473. PMC 1150163. PMID 2006911.
Davrinche C, Abbal M, Clerc A (1991). "Molecular characterization of human complement factor B subtypes". Immunogenetics. 32 (5): 309–312. doi:10.1007/bf00211644. PMID 2249879. S2CID 13698345.
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): 667–675. doi:10.1042/bj2530667. 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): 331–342. doi:10.1016/0092-8674(87)90436-3. PMID 3643061. S2CID 32752642.
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): 4464–4468. Bibcode:1983PNAS...80.4464C. 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): 153–157. doi:10.1002/j.1460-2075.1984.tb01776.x. 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. doi:10.1042/bj2090061. 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): 3407–3412. doi:10.1016/S0021-9258(17)43108-5. 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): 5661–5665. Bibcode:1982PNAS...79.5661W. 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): 171–174. 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 U.S. National Library of Medicine Medical Subject Headings (MeSH)
Overview of all the structural information available in the PDB for UniProt: P00751 (Complement factor B) at the PDBe-KB.

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[refGRCh38Ensembl-1] 1 2 3 ENSG00000239754, ENSG00000243649, ENSG00000241253, ENSG00000242335, ENSG00000241534, ENSG00000204359 GRCh38: Ensembl release 89: ENSG00000243570, ENSG00000239754, ENSG00000243649, ENSG00000241253, ENSG00000242335, ENSG00000241534, ENSG00000204359 – Ensembl, May 2017

[refGRCm38Ensembl-2] 1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000090231 – Ensembl, May 2017

[3] "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[4] "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[entrez-5] 1 2 "Entrez Gene: CFB complement factor B".

[Bentley_1986-6] 1 2 Bentley DR, Campbell RD (1986). "C2 and factor B: structure and genetics". Biochemical Society Symposium. 51: 7–18. PMID 3101701.

v t e Endopeptidases: serine proteases/serine endopeptidases (EC 3.4.21)
Digestive enzymes	Enteropeptidase Trypsin Chymotrypsin Elastase Neutrophil Pancreatic
Coagulation	factors: Thrombin Factor VIIa Factor IXa Factor Xa Factor XIa Factor XIIa Kallikrein PSA KLK1 KLK2 KLK3 KLK4 KLK5 KLK6 KLK7 KLK8 KLK9 KLK10 KLK11 KLK12 KLK13 KLK14 KLK15 fibrinolysis: Plasmin Plasminogen activator Tissue-type plasminogen activator Urinary plasminogen activator
Complement system	Factor B Factor D Factor I MASP MASP1 MASP2 C3-convertase
Other immune system	Chymase Granzyme Tryptase Proteinase 3/Myeloblastin
Venombin	Ancrod Batroxobin
Other	Acrosin Prolyl endopeptidase Pronase Proprotein convertases 1 2 Prostasin Reelin Subtilisin/Furin/S1P4 Sedolisin/TPP1 Streptokinase Cathepsin A G

Complement factor B

Function

References

Further reading

External links