The T-cell receptor ζ chain contains a GTP/GDP binding site

Marcus E. Peter*, Craig Hall, Andreas Rühlmann, Jaime Sancho, Cox Terhorst

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


In a search for nucleotide binding proteins associated with the T-cell receptor (TCR) -CD3 complex, a novel labeling technique involving introduction of [α-32P]GTP or [α-32P]ATP into permeabilized cells followed by in situ periodate oxidation was developed. To test the method we first demonstrated that p21ras and other classical GTP binding proteins could be labeled in a GTP-specific manner. In human T lymphocytes the TCR ζ chain was found to be specifically labeled by GTPoxi but not by ATPoxi or CTPoxi. Labeling kinetics and competition experiments demonstrated that f had a capacity to bind GTP and GDP but not GMP or ATP. Proteolytic cleavage experiments identified lysine 128 as the GTP crosslinking site. This result was confirmed by studies using oligonucleotide-directed mutagenesis. Lysine residues 128, 135 and 149 were each replaced by arginine and glycine 134 by valine and mutated proteins were expressed in CHO cells. Labeling of mutants K128R and G134V was abrogated whereas mutant proteins K135R and K148R could still be specifically crosslinked to GTP. We conclude that Lys128 and Gly134 are part of a GTP/GDP binding site suggesting that ζ is a unique GTP/GDP binding structure.

Original languageEnglish (US)
Pages (from-to)933-941
Number of pages9
JournalEMBO Journal
Issue number3
StatePublished - 1992


  • GTP binding protein
  • In situ affinity labeling
  • Mutagenesis
  • P21h-
  • T-cell receptor ζ chain

ASJC Scopus subject areas

  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology
  • Molecular Biology
  • General Neuroscience


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