Open AccessNtk: a Csk-related protein-tyrosine kinase expressed in brain and T lymphocytes.
Author(s) -
Lionel M.L. Chow,
Courtney Jarvis,
Qiongzheng Hu,
Steven H. Nye,
François G. Gervais,
André Veillette,
Louis A. Matis
Publication year - 1994
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.91.11.4975
Subject(s) - proto oncogene tyrosine protein kinase src , chemistry , sh2 domain , tyrosine , tyrosine phosphorylation , tyrosine kinase , sh3 domain , tyrosine protein kinase csk , protein tyrosine phosphatase , biochemistry , phosphorylation , microbiology and biotechnology , receptor tyrosine kinase , signal transduction , biology
The activity of Src-related protein-tyrosine kinases is repressed by the phosphorylation of a conserved carboxyl-terminal tyrosine by another cytoplasmic protein-tyrosine kinase termed p50csk. In this study, we characterize Ntk, a protein-tyrosine kinase bearing striking similarities to p50csk. Like p50csk, Ntk possesses Src homology 3 and Src homology 2 domains and lacks the consensus tyrosine phosphorylation and myristoylation sites found in members of the Src family. Expression of ntk transcripts was maximal in brain, and was observed at significant levels in thymus and spleen. ntk RNA levels were dramatically reduced upon mitogenic stimulation of normal T lymphocytes and were minimal in transformed T-cell populations. Firm evidence that Ntk is a Csk-related enzyme was provided by the observation that it phosphorylated a Src-related polypeptide on the inhibitory carboxyl-terminal tyrosine. These findings indicate that Ntk is a Csk-related enzyme that may play an inhibitory role in the control of T-cell proliferation.