The Fc receptor (FcR) gamma subunit is essential for IgE-binding activity of cell-surface expressed chimeric receptor molecules constructed from human high-affinity IgE receptor (Fc epsilon RI) alpha and FcR gamma subunits.
The Fc receptor (FcR) gamma subunit was originally discovered as a homodimeric subunit of the high-affinity IgE receptor (FcepsilonRI). But it was recently found to be a common signal-generating subunit of Fc receptors including IgG Fc receptors (FcgammaRs) and IgA Fc receptor (FcalphaR), and furthermore to generate a signal also with stimuli through non-immune receptors. In addition, it plays an essential role in cell-surface expression of the FcepsilonRI and the FcgammaRIIIA isoform and also regulates cell-surface expression and ligand-binding affinity of the FcgammaRI. In this report, we addressed the possibility that the FcRgamma could affect the correct folding of the IgE-binding region of the FcepsilonRIalpha subunit by using the chimeric receptor molecules constructed from human FcepsilonRIalpha and FcRgamma. Furthermore, we demonstrated that the seven amino acid residues in the C-terminal region on the extracellular domain of the FcepsilonRlalpha were essential for maintaining the IgE-binding activity of the FcepsilonRIalpha exodomain on the cell membrane and/or may affect the correct folding of the alpha subunit itself within the cell.
Suzuki
K
K
Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan.
Hirose
T
T
Matsuda
H
H
Hasegawa
S
S
Okumura
K
K
Ra
C
C
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D011817:Rabbits; D051381:Rats; D017455:Receptors, IgE / Q000737:chemistry / Q000235:genetics*; D017452:Receptors, IgG / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000138:chemical synthesis / Q000378:metabolism*; D014162:Transfection / Q000276:immunology
D008565:Membrane Proteins; D017455:Receptors, IgE; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D007073:Immunoglobulin E