Ntk: A Csk-Related Protein-Tyrosine Kinase Expressed in Brain and T Lymphocytes

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...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1994-05, Vol.91 (11), p.4975-4979
Main Authors: Lionel M. L. Chow, Jarvis, Christopher, Hu, Qile, Nye, Steven H., Gervais, Francois G., Veillette, Andre, Matis, Louis A.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Biochemistry
Brain
Brain - metabolism
Cells, Cultured
Cloning, Molecular
Complementary DNA
Enzymes
Genes
Immunity (Disease)
Lymphocyte Activation
Mice
Mice, Inbred BALB C
Molecular Sequence Data
Phosphorylation
Protein-Tyrosine Kinases - biosynthesis
Proteins
Proto-Oncogene Proteins pp60(c-src)
RNA
Sequence Homology, Amino Acid
Spleen
Spleen cells
Splenocytes
T lymphocytes
T-Lymphocytes - metabolism
Yeasts
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Summary: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.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.91.11.4975