title: A minimal receptor-Ig chimera of human FcepsilonRI alpha-chain efficiently binds secretory and membrane IgE.
abstract: We constructed a soluble minimal receptor-Ig chimera in which the two extracellular domains of human Fcepsilonhain (D1 and D2) were fused to the dimerizing C-terminal domain of human IgG1 heavy chain (gamma1-CH3). The protein was expressed and actively secreted by Chinese hamster ovary (CHO) cells as a fully glycosylated soluble dimeric protein. It showed efficient binding both to human membrane-bound IgE isoforms and to the two secretory IgE isoforms. Moreover, the dimeric receptor binds IgE with the expected 1:2 stoichiometry. The receptor-Ig chimera, in 2-fold molar excess, inhibited engagement of secretory IgE to rat basophilic leukemia cells expressing the human alphabetagamma receptor. Full self-nature and inability to bind Fcgamma receptors make this protein an attractive candidate for clinical applications and a novel biotechnological tool for atopic allergy research.
authors.affiliation: Molecular Immunology, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Vangelista
authors.forename: Michela
authors.initials: M
authors.lastname: Cesco-Gaspere
authors.forename: Roberto
authors.initials: R
authors.lastname: Lorenzi
authors.forename: Oscar
authors.initials: O
authors.lastname: Burrone
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D019281:Dimerization; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism*; D007074:Immunoglobulin G / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D051381:Rats; D017455:Receptors, IgE / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility
chemical_list: D007074:Immunoglobulin G; D008565:Membrane Proteins; D020033:Protein Isoforms; D021122:Protein Subunits; D017455:Receptors, IgE; D011993:Recombinant Fusion Proteins; D007073:Immunoglobulin E