A range of Cɛ3-Cɛ4 interdomain angles in IgE Fc accommodate binding to its receptor CD23

• Published in: Acta crystallographica. Section F, Structural biology communications Structural biology communications, 2014-03, Vol.70 (3), p.305-309
• Main Authors: Dhaliwal, Balvinder, Pang, Marie O. Y., Yuan, Daopeng, Beavil, Andrew J., Sutton, Brian J.
• Format: Article
• Language: English
• Subjects: CD23; Crystallography, X-Ray; Fcɛ3-4; Humans; Hydrogen Bonding; immunoglobin E; Immunoglobulin E - chemistry; Immunoglobulin Fc Fragments - chemistry; Models, Molecular; Protein Binding; Protein Interaction Domains and Motifs; Protein Structure, Quaternary; Protein Structure, Secondary; Receptors, IgE - chemistry
• ISSN: 2053-230X; 2053-230X
• DOI: 10.1107/S2053230X14003355

The antibody IgE plays a central role in allergic disease, functioning principally through two cell‐surface receptors: FcɛRI and CD23. FcɛRI on mast cells and basophils mediates the immediate hypersensitivity response, whilst the interaction of IgE with CD23 on B cells regulates IgE production. Crystal structures of the lectin‐like `head' domain of CD23 alone and bound to a subfragment of IgE consisting of the dimer of Cɛ3 and Cɛ4 domains (Fcɛ3‐4) have recently been determined, revealing flexibility in the IgE‐binding site of CD23. Here, a new crystal form of the CD23–Fcɛ3‐4 complex with different molecular‐packing constraints is reported, which together with the earlier results demonstrates that conformational variability at the interface extends additionally to the IgE Fc and the quaternary structure of its domains.