Distinct domains of the CD3-gamma chain are involved in surface expression and function of the T cell antigen receptor

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The T cell antigen receptor (TcR) is a multisubunit complex that consists of at least six different polypeptides. We have recently demonstrated that the CD3-delta subunit cannot substitute for the CD3-gamma subunit in TcR cell surface expression, in spite of significant amino acid homology between these two subunits. To identify CD3-gamma-specific domains that are required for assembly of the complete TcR and for surface expression and function of the TcR, chimeric CD3-gamma/CD3-delta molecules were constructed and expressed in T cells devoid of endogenous CD3-gamma. Substitution of the extracellular domain of CD3-gamma with that of CD3-delta did not allow cell surface expression of the TcR. In contrast, substitution of the transmembrane and/or the intracellular domains of CD3-gamma with those of CD3-delta did allow TcR cell surface expression. These results conclusively demonstrate that the extracellular domain of CD3-gamma plays a unique role in TcR assembly. Functional analyses of the transfectants demonstrated that the intracellular domain of CD3-gamma is required for protein kinase C-mediated down-regulation of TcR but is dispensable for the pattern of tyrosine phosphorylation observed following activation through TcR.
Original languageEnglish
JournalJournal of Biological Chemistry
Issue number9
Pages (from-to)4675-80
Number of pages5
Publication statusPublished - 1995

Bibliographical note

Keywords: Antigens, CD3; Cell Line; Down-Regulation; Humans; Phosphotyrosine; Protein Kinase C; Protein Processing, Post-Translational; Receptors, Antigen, T-Cell; Recombinant Fusion Proteins; Transfection; Tyrosine

ID: 8545862