The C1q receptor site on immunoglobulin G

Abstract

We propose that, the binding site for the complement subcomponent C1q on immunoglobulin G involves the last two (C-terminal) β-strands of the C_γ2 domain. This region contains a large number of accessible and highly conserved charged residues and charge is postulated as an important component of the C1q–IgG interaction. The conclusions are reached on the basis of accessibility and sequence conservation analyses of C_γ2 amino acid residues, the use of specific inhibitors and chemical modification studies.