Tyrosyl phosphorylation and activation of MAP kinases by p56lck

Elham Ettehadieh, Jasbinder S. Sanghera, Steven L. Pelech, Denise Hess-Bienz, Julian Watts, Nilabh Shastri, Ruedi Aebersold

Research output: Contribution to journalArticlepeer-review


T cell signaling via the CD4 surface antigen is mediated by the associated tyrosyl protein kinase p56lck. The 42-kilodalton mitogen-activated protein (MAP) kinase (p42mapk) was tyrosyl-phosphorylated and activated after treatment of the murine T lymphoma cell line 171CD4+, which expresses CD4, with antibody to CD3. Treatment of the CD4-deficient cell line 171 with the same antibody did not result in phosphorylation or activation of p42mapk. Purified p56lck both tyrosyl-phosphorylated and stimulated the seryl-threonyl phosphotransferase activity of purified p44 mpk, a MAP kinase isoform from sea star oocytes. A synthetic peptide modeled after the putative regulatory phosphorylation site in murine p42 mapk (Tyr185) was phosphorylated by p56lck with a similar Vmax, but a fivefold lower Michaelis constant (K m) than a peptide containing the Tyr394 autophosphorylation site from p56lck. MAP kinases may participate in protein kinase cascades that link Src family protein-tyrosyl kinases to seryl-threonyl kinases such as those encoded by rsk and raf, which are putative substrates of MAP kinases.

Original languageEnglish (US)
Pages (from-to)853-855
Number of pages3
Issue number5046
StatePublished - Jan 1 1992
Externally publishedYes

ASJC Scopus subject areas

  • General


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