Human Fcγ Fragment: Location of Acidic Residues Involved in Complement Activation

Classical activation of the complement system is initiated by the binding of C1 to immune complexes or aggregated IgG1. It is generally assumed that the binding site for the complement subcomponent C1q resides on the Cγ2 domain. However, a convincing picture of the precise topography and chemical nature of the complement binding site is still lacking.