Complement factor 5 C5b Activation of C5 Authored: de Bono, B, 2004-08-04 09:17:50 EC Number: 3.4.21 ISBN0781735149 Reactome Database ID Release 43173680 Reactome, http://www.reactome.org ReactomeREACT_7989 Reviewed: D'Eustachio, P, 2006-07-03 21:35:13 The same complexes as for C3 activation are employed for the cleavage of C5. C3 convertases with an additional C3b molecule covalently deposited in the immediate vicinity form the C5 convertases C3b,Bb,C3b and C4b,2a,3b, respectively. The second C3b acts like an anvil for C5: it interacts with C5 and presents C5 in the correct conformation for cleavage by the C2a or Bb enzyme.