C4b-binding protein (C4BP) is a regulator of the classical complement pathway C3
convertase (C4bC2a complex). It is a disulfide-linked polymer of seven α-chains and a
unique β-chain; the α-and β-chains are composed of eight and three complement control
protein (CCP) domains, respectively. To elucidate the importance of the polymeric nature of
C4BP and the structural requirements for the interaction between C4b and the α-chain, 19
recombinant C4BP variants were created. Six truncated monomeric variants, nine polymeric …