Characterization of the GTP/GDP binding site in the murine CD3-ζ polypeptide chain

Rafael Franco*, Marcus E. Peter, Myung Sik Choi, Bernard Malissen, Jaime Sancho, Cox Terhorst

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Using a newly developed in situ affinity-labeling method of nucleotide-binding proteins (NTPoxi technique) we discovered that the human T-cell receptor-associated CD3-ζ protein might bind GTP/GDP. To further characterize GTP/GDP binding to CD3-ζ, murine T-cell lines expressing ζζ homodimers or CD3-ζ/FcεR1γ heterodimers were used. Specific GTPoxi labeling of CD3-ζ was found in all murine T cells in which a complete CD3-ζ polypeptide chain was expressed, including cells in which CD3-ζ was disulfide bridged to the FcεR1γ chain. In murine T cells the kinetics of labeling of CD3-ζ was similar to that of small G-proteins. Upon activation of murine T cells a slight but significant increase in GTPoxi labeling of CD3-ζ was detected. Whether all 3 so-called 'Reth motifs' (ζA, ζB and/or ζC) were necessary for the binding of GTP/GDP was addressed by using cells expressing truncated CD3-ζ molecules. Whereas truncated CD3-ζ, in which ζA and part of ζB were deleted, was still able to bind GTP, upon deletion of all 3 Reth motifs cross-linking by the GTPoxi method became impossible. Regardless of whether this implies a direct or indirect binding of GTP/GDP to CD3-ζ, these nucleotides and their hydrolysis must play an important role in T-cell activation through the TCR/CD3 complex.

Original languageEnglish (US)
Pages (from-to)167-175
Number of pages9
JournalImmunology Letters
Volume43
Issue number3
DOIs
StatePublished - Dec 1994

Keywords

  • CD3 complex
  • GTP binding protein
  • T lymphocyte
  • T-cell receptor
  • ζ chain

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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