CFB - Complement factor B - human protein (Function)
Home Recent activites arrow-down favorite My favorites arrow-down favorite My labels arrow-down Downloads
Back to ...  
Publication View

CFB »  Complement factor B   [ EC ]
Protein also known as:  Glycine-rich beta glycoprotein (GBG). Cleaved into:  Complement factor B Ba fragment; Complement factor B Bb fragment.
Gene name:  CFB
Family name: Peptidase S1
Entry whose protein(s) existence is based on evidence at protein level
extend overview
1 84 2


 show evidences
Factor B which is part of the alternate pathway of the complement system is cleaved by factor D into 2 fragments: Ba and Bb. Bb, a serine protease, then combines with complement factor 3b to generate the C3 or C5 convertase. It has also been implicated in proliferation and differentiation of preactivated B-lymphocytes, rapid spreading of peripheral blood monocytes, stimulation of lymphocyte blastogenesis and lysis of erythrocytes. Ba inhibits the proliferation of preactivated B-lymphocytes.  
  • CuratedUniProtKB
GO molecular function 
Complement bindingdefinition[GO:0001848]  
  • TASUniProtKB
GO biological process 
Complement activation, alternative pathwaydefinition[GO:0006957]  
  • NASUniProtKB
  • IEAUniProtKB KW
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC Cleavage of Arg-|-Ser bond in complement component C3 alpha-chain to yield C3a and C3b, and Arg-|-Xaa bond in complement component C5 alpha-chain to yield C5a and C5b.  
  • CuratedUniProtKB
More information is available from:
According to KEGG, this protein belongs to the following pathways:
Complement and coagulation cascades  hsa04610+629  
Staphylococcus aureus infection  hsa05150+629  
According to Reactome, this protein belongs to the following pathways:
Activation of C3 and C5  REACT_7972  
Alternative complement activation  REACT_8001  
Regulation of Complement cascade  REACT_118707  


Biological process 
Complement alternate pathway  definition   [KW-0179]
Immunity  definition   [KW-0391]
Innate immunity  definition   [KW-0399]
Molecular function 
Hydrolase  definition   [KW-0378]
Protease  definition   [KW-0645]
Serine protease  definition   [KW-0720]
Technical term 
Reference proteome  definition   [KW-1185]

Further external links

GeneWiki: Complement_factor_B
GenomeRNAi: 629
PRO: PR:P00751