Figure 5

Binding model. Our data supports that the conformational entropy modulated by galactose governs the binding affinity of IgG to FcγRIIIa. The terminal galactose moiety stabilizes the hinge α-helical peptide located at the interface between the CH2 and CH3 domains. In the presence of N-glycans containing galactose, the CH2 domain remains in a more rigid conformation than that in the agalactosylated G0F glycoform. The rigid conformation yields a less unfavorable entropy change, facilitating the binding to FcγRIIIa. IgG-Fc and FcγRIIIa are represented in gray, and light orange respectively.