Identification of a linear epitope for Fc-binding in the mouse FcγRIII.

Abstract Fc receptors are transmembrane proteins, found on the surfaces of immune cells, that aid in the removal of foreign pathogens by binding to antibody-coated targets via the Fc regions of the antibodies. To identify sites on mouse FcγRIII (moFcγRIII) α-chain that bind to the Fc region, peptides derived from the proximal extracellular domain (EC2) of moFcγRIII α-chain corresponding to the homologous region of human FcγRIIIB α-chain were synthesized. Binding of mouse IgG to the different peptides was tested by Dot-blot assay. The effective peptide 119 SFFHNEKSVRYH 130 located in the putative C–C′ loop of the EC2 domain was found to bind mouse IgG specifically with an affinity of approximately 5.58 × 10 −5  M and inhibit the binding of mouse IgG to the receptor. Such a functional peptide should be very useful for further understanding the IgG–FcγR interaction and development of FcR-targeting drugs.