Biochemical and genetic analyses of the Tec kinases Itk and Rlk/Txk

M. J. Czar, J. Debnath, E. M. Schaeffer, C. M. Lewis, P. L. Schwartzberg

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


The Tec kinases have been implicated as important components of signalling pathways downstream of lymphocyte antigen receptors. Activation of these kinases requires two steps: (i) phosphorylation by Src family kinases and (ii) plasma membrane localization, which is mediated by interaction between the pleckstrin homology (PH) domains of Tec kinases and the products of phosphoinositide-3 kinase (PI-3K). Irk and Rlk/Txk are Tec kinases expressed in T-lymphocytes. Despite similarity to other Tec kinases, Rlk/Txk lacks a PH domain and instead possesses a palmitoylated cysteine-string motif. We have found that both Rlk/Txk and Itk are phosphorylated in response to T-cell receptor stimulation and can be activated by phosphorylation by Src family kinases. However, consistent with its lack of PH domain, Rlk/Txk is phosphorylated independent of PI-3K activity. Furthermore, we demonstrated that like Itk, Rlk/Txk is associated with lipid RAFTs (detergent-insoluble, cholesterol-rich regions of the membrane), but unlike Itk, Rlk/Txk's RAFT association is independent of PI-3K activity. Despite these differences, Rlk/Txk partially compensates for loss of Itk in gene-targeted animals, suggesting overlapping functions for these kinases.

Original languageEnglish (US)
Pages (from-to)863-867
Number of pages5
JournalBiochemical Society Transactions
Issue number6
StatePublished - 2001
Externally publishedYes


  • Phosphatidylinositol 3-kinase
  • RAFTs
  • T lymphocytes
  • Tyrosine kinase

ASJC Scopus subject areas

  • Biochemistry


Dive into the research topics of 'Biochemical and genetic analyses of the Tec kinases Itk and Rlk/Txk'. Together they form a unique fingerprint.

Cite this