TCR isoform containing the Fc receptor {gamma} chain exhibits structural and functional differences from isoform containing CD3{xi} |
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Authors: | Ohno Hiroshi; Aoe Tomohiko; Ra Chisei; Yamamoto Tadashi; Saito Takashi |
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Institution: | Division of Molecular Genetics, Center for Biomedical Science, Chiba University, School of Medicine 1-8-1 Inohana, Chuo-ku, Chiba 260, Japan
1 Department of Immunology, Juntendo University, School of Medicine 2-1-1 Hongo, Bunkyo-ku, Tokyo 113, Japan
2 Department of Oncology, The Institute of Medical Science, The University of Tokyo 4-6-1 Shiroganedai, Minato-ku, Tokyo 108, Japan |
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Abstract: | The structure and function of the TCR-CD3 complex containinga homodimer of the gamma chain of the high affinity receptorfor IgE (FcR ) (FcR + TCR) was investigated by transfecting theFcR gene into a CD3 –, CD3 –, FcR – T cell line.Introduction of FcR , as well as CD3 , induced a high expressionof the TCR-CD3 complex on the cell surface. Transfected FCR formed a homodimer and associated firmly with the TCR ßdimer but only weakly with the CD3![{gamma}](http://intimm.oxfordjournals.org/math/gamma.gif) ![{delta}](http://intimm.oxfordjournals.org/math/delta.gif) . Stimulation of both FcR and CD3 transfectants by antibodies against TCR or CD3 inducedaccumulation of inositol phosphates, the Ca2+ response, IL-2production, and growth inhibition. On the other hand, antigenstimulation of transfectants expressing FcR as well as CD3 inducedIL-2 production, but only the latter exhibited the antigen-inducedgrowth inhibition. In vitro kinase assay suggested that theCD3 dimer but not the FcR dimer associates with the Fyn kinase.These results indicate that the FcR homodlmer Is able to forma functional TCR complex but that the mode of assembly and thesignaling function of FcR + TCR, including its association withtyrosine klnase(s), may differ from the TCR-CD3 complex containingCD3 homodimers ( + TCR). This provides an example which illustratesthat different TCR isoforms mediate distinct signals and functions. |
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Keywords: | assembly of TCR-CD3 complexes protein tyrosine kinase signal transduction TCR isoforms transfection |
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