The IgG Fc Contains Distinct Fc Receptor (FcR) Binding Sites: The Leukocyte Receptors FcγRI and FcγRIIa Bind to a Region in the Fc Distinct from That Recognized by Neonatal FcR and Protein A

• DOI: 10.4049/jimmunol.164.10.5313
• Publication Date: 2014-04-22T02:30:08Z
• Authors: Bruce D. Wines; Maree S. Powell; Paul W. H. I. Parren; Nadine Barnes; P. Mark Hogarth
• Keywords: Fragment crystallizable region; Neonatal Fc receptor; Immunoglobulin Fc Fragments; Fc receptor; Immunoglobulin domain

The CH2-CH3 interface of the IgG Fc domain contains binding sites for a number receptors including Staphylococcal protein A and neonatal receptor (FcRn). It has recently been proposed that also principal site an isoform low affinity II (Fc gamma RIIb). RI RII have previously mapped to lower hinge adjacent surface CH2 although contributions suggested. This study addresses question whether plays role in interaction with RIIa. We demonstrate recombinant soluble murine human RIIa did not compete FcRn IgG, therefore appears be involved binding. importance was confirmed by introducing mutations (LL234,235AA) which abrogated IgG1. conclude region is critical between whereas appear insignificant.