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ENZYME entry: EC 3.4.21.47

Accepted Name
alternative-complement-pathway C3/C5 convertase.
Alternative Name(s)
C3 convertase.
C3 proactivator.
C5 convertase.
complement component C3/C5 convertase (alternative).
complement factor B.
properdin factor B.
Reaction catalysed
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
Comment(s)
  • A bimolecular complex of complement fragment Bb with either C3b or cobra venom factor; Bb contains the active site.
  • Bb is formed by cleavage of proenzyme factor B by factor D.
  • Cleavage of complement component C5 requires additional C3b which binds C5 and renders it susceptible to cleavage by C3b,Bb complex.
  • C3b,Bb is stabilized in plasma by factor P.
  • Belongs to peptidase family S1.
Cross-references
BRENDA3.4.21.47
EC2PDB3.4.21.47
ExplorEnz3.4.21.47
PRIAM enzyme-specific profiles3.4.21.47
KEGG Ligand Database for Enzyme Nomenclature3.4.21.47
IUBMB Enzyme Nomenclature3.4.21.47
IntEnz3.4.21.47
MEDLINEFind literature relating to 3.4.21.47
MetaCyc3.4.21.47
Rhea expert-curated reactions3.4.21.47
UniProtKB/Swiss-Prot
P81187, CFAB_BOVIN;  Q864V9, CFAB_GORGO;  P00751, CFAB_HUMAN;  
P04186, CFAB_MOUSE;  Q864W0, CFAB_PANTR;  Q03710, CFAB_PIG;  
Q864W1, CFAB_PONPY;  

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