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Necessity of the stalk region for immunoglobulin E interaction with CD23
Author(s) -
Chen BingHung,
Ma Check,
Caven Timothy H.,
ChanLi Yee,
Beavil Andrew,
Beavil Rebecca,
Gould Hannah,
Conrad Daniel H.
Publication year - 2002
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.2002.01512.x
Subject(s) - cd23 , immunoglobulin e , amino acid , biology , leucine zipper , mutant , microbiology and biotechnology , fusion protein , antibody , chemistry , peptide sequence , biochemistry , gene , genetics , recombinant dna
Summary Previously, a soluble mouse CD23 chimera, composed of an N‐terminal trimeric isoleucine zipper motif ( lz ) followed by the entire extracellular region (amino acids 48–331) of CD23 ( lz ‐CD23 48−331 ), was prepared and exhibited strong binding to rodent immunoglobulin E (IgE). In the current study, we report the construction of a similar human chimeric protein ( lz ‐huCD23 45−321 ), as well as a series of murine chimeric lz‐ CD23 mutants with incremental portions of stalk deleted, to further investigate the role of the stalk region in mediating the CD23–IgE interaction. All chimeric proteins were designed such that the predicted heptad structure of the stalk was retained. IgE binding, as determined by the capacity to inhibit 125 I‐IgE from binding to FcεRI‐bearing RBL‐2H3 cells, and by surface plasmon‐resonance analysis using an IgE‐coated sensor chip, was unchanged from the original lz chimera and the binding parameters were similar to those of cell‐surface CD23. The minimal murine chimera that retained IgE‐binding activity was lz ‐CD23 139−331 , which still contains 35 amino acids of the stalk region. When the lz motif was linked to CD23 amino acid 157 (or higher), significant IgE‐binding capacity was lost. With human lz ‐CD23, as with mouse, deletion of the stalk greatly reduced IgE‐binding ability. In summary, the data support the concept that at least a portion of the stalk region of CD23 plays a crucial role in maintaining high‐affinity/avidity interaction with IgE. The lz ‐CD23 constructs represent a possible alternative for both blocking the IgE/FcεRI interaction and inhibiting IgE production by B lymphocytes.