Participation of the N-terminal region of Cε3 in the binding of human IgE to its high-affinity receptor FcεRI

Abstract

The binding of immunoglobulin E (IgE) to its high-affinity receptor (FcεRI) expressed on mast cells and basophils is central to the development of an allergic reaction. Previous studies have implicated the third constant domain of IgE-Fc (Cε3) as the site of the interaction with FcεRI. We have prepared a series of site-directed mutants of human IgE-Fc, particularly focusing on the N-terminal 'linker' region and AB loop of Cε3. The kinetics of binding IgE and its Fc fragments to the immobilized receptor were determined by surface plasmon resonance (SPR), and two phases of binding were observed. We identified one mutation in the N-terminal linker region, R334S, that has a dramatic effect on bi..