T cell receptor-induced phosphorylation of Sos requires activity of CD45, Lck, and protein kinase C, but not ERK

Haoran Zhao, Yi Yang Li, Raymond V. Fucini, Susan E. Ross, Jeffrey E. Pessin, Gary A. Koretzky

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Stimulation of the T cell antigen receptor (TCR) activates signaling pathways involving protein kinases, phospholipase Cγ1, and Ras. How these second messengers interact to initiate distal activation events is an area of intense scrutiny. In this report, we confirm that TCR ligation results in phosphorylation of Sos, a guanine nucleotide exchange factor for Ras. This requires expression of both the CD45 tyrosine phosphatase and the Lck protein tyrosine kinase and depends upon signaling via protein kinase C. In contrast to previous studies examining requirements for Sos phosphorylation following insulin and epidermal growth factor receptor engagement, we show that TCR- induced phosphorylation of Sos does not require activation of the mitogen- activated protein kinase/extracellular-signal regulated kinase (MEK/ERK) pathway. However, the basal phosphorylation of Sos in T cells is affected by either MEK or MEK-dependent kinases. Although Sos phosphorylation results in its dissociation from Grb2 following insulin stimulation in Chinese hamster ovary cells, TCR engagement on the Jurkat T cell line fails to elicit a similar effect. These data demonstrate that the kinases responsible for Sos phosphorylation differ following ligation of various cell surface receptors and that the consequences of Sos phosphorylation relies, at least in part, on sites of its phosphorylation.

Original languageEnglish (US)
Pages (from-to)21625-21634
Number of pages10
JournalJournal of Biological Chemistry
Volume272
Issue number34
DOIs
StatePublished - Aug 22 1997

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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