Activating and inhibitory mutations in adjacent tyrosines in the kinase domain of ZAP-70

R. L. Wange, R. Guitian, N. Isakov, J. D. Watts, R. Aebersold, L. E. Samelson

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168 Scopus citations


ZAP-70 is a 70-kDa protein tyrosine kinase, expressed exclusively in T cells and NK cells, and plays a critical role in mediating T cell activation in response to T cell receptor engagement. The strong correlation between tyrosine phosphorylation of ZAP-70 and its acquisition of increased kinase activity suggests that it is positively regulated by tyrosine phosphorylation. Previously, we identified tyrosines 492 and 493 of ZAP-70 as being sites of in vivo phosphorylation in response to T cell receptor engagement. To determine the role of phosphorylation in regulating ZAP-70 activity, we mutated each of these tyrosines individually to phenylalanine. When expressed in COS cells, Y493F-mutated ZAP-70 demonstrated normal basal kinase activity, but, unlike wild type ZAP-70, could not be activated by tyrosine phosphorylation induced by incubation with pervanadate or by co- expression of constitutively activated Lck. This suggests that Tyr-493 phosphorylation is required for the tyrosine phosphorylation-induced activation of ZAP-70. The Y492F mutation resulted in 4-fold higher basal kinase activity, which could he stimulated further by tyrosine phosphorylation. These results reveal that critical tyrosine residues in the kinase domain of ZAP-70 are important in regulation of its catalytic activity.

Original languageEnglish
Pages (from-to)18730-18733
Number of pages4
JournalJournal of Biological Chemistry
Issue number32
StatePublished - 1 Jan 1995
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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