Interactions between the Protein-tyrosine Kinase ZAP-70, the Proto-oncoprotein Vav, and Tubulin in Jurkat T Cells (*)
- From the Division of Cellular Immunology, The National Institute for Medical Research, Mill Hill, The Ridgeway, London NW7 1AA, United Kingdom
- § To whom correspondence should be addressed.
Abstract
Two molecules involved in signal transduction via the T cell antigen receptor, namely the protein-tyrosine kinase ZAP-70 and the proto-oncoprotein Vav, were found to be constitutively associated with tubulin in Jurkat T cells. Both were able to bind to tubulin independently of one another, as determined by transient transfection into COS-7 cells. The ZAP-70 associated with tubulin was preferentially tyrosine-phosphorylated after T cell antigen receptor stimulation of Jurkat T cells, suggesting that this interaction was functionally significant. Vav was also found to co-immunoprecipitate with ZAP-70 from cell extracts depleted of tubulin. This raised the possibility that Vav might be a substrate for ZAP-70 protein-tyrosine kinase activity. However, tyrosine phosphorylation of Vav preceded that of ZAP-70, indicating that Vav was unlikely to be a downstream target of ZAP-70. The association of ZAP-70 and Vav with tubulin implies that the microtubules may be involved in the signaling function of these two molecules, perhaps by targeting them to their appropriate intracellular location.
Footnotes
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↵* This work was supported by the Medical Research Council and by European Community Biotech Grant 920164. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- TCR
-
T cell antigen receptor
- GST
-
glutathione S-transferase
- Tyr(P)
-
phosphotyrosine
- PTK
-
protein-tyrosine kinase
- IPB
-
immunoprecipitation buffer
- FCS
-
fetal calf serum
- DMEM
-
Dulbecco's modified Eagle's medium
- PBS
-
phosphate-buffered saline
- PIPES
-
1,4-piperazinediethanesulfonic acid
- ITAM
-
immunoreceptor tyrosine-based activation motif.
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- Received August 14, 1995.
- Revision received October 11, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
