Figure 1. Organization and conformational rearrangements of the IgE-Fc.

(a) IgE and the relative locations of the FcɛRIα- (purple) and CD23 (orange)-binding sites. (b) A representation of open and closed conformations of the IgE-Fc_3–4 domains (including the IgE–G335C–Fc_3–4 mutant locked in a closed conformation), and a representation of the reciprocal allosteric inhibition by FcɛRIα (purple) and CD23 (orange). (c) A schematic of the bent conformation of IgE, and the relative position of the Cɛ2 domains.