C2 - Complement C2 - human protein (Function)
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C2 »  Complement C2   [ EC ]
Protein also known as:  C3/C5 convertase. Cleaved into:  Complement C2a fragment; Complement C2b fragment.
Gene name:  C2
Family name: Peptidase S1
Entry whose protein(s) existence is based on evidence at protein level
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Component C2 which is part of the classical pathway of the complement system is cleaved by activated factor C1 into two fragments: C2b and C2a. C2a, a serine protease, then combines with complement factor 4b to generate the C3 or C5 convertase.  
  • CuratedUniProtKB
GO molecular function 
Serine-type endopeptidase activitydefinition[GO:0004252] silver  
  • IEAInterPro 2 GO
GO biological process 
Complement activation, classical pathwaydefinition[GO:0006958]  
  • IEAUniProtKB KW
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC Selective cleavage of Arg-|-Ser bond in complement component C3 alpha-chain to form C3a and C3b, and Arg-|-Xaa bond in complement component C5 alpha-chain to form C5a and C5b.  
  • CuratedUniProtKB
More information is available from:
According to KEGG, this protein belongs to the following pathways:
Complement and coagulation cascades  hsa04610+717  
Pertussis  hsa05133+717  
Staphylococcus aureus infection  hsa05150+717  
Systemic lupus erythematosus  hsa05322+717  
According to Reactome, this protein belongs to the following pathway:
Immune System  REACT_6900  
C2 is a major histocompatibility complex class-III protein.  
  • CuratedUniProtKB


Biological process 
Complement pathway  definition   [KW-0180]
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_component_2
GenomeRNAi: 717
PRO: PR:P06681