Epidermal growth factor (EGF) receptor T669 peptide kinase from 3T3-L1 cells is an EGF-stimulated "MAP" kinase

Proc Natl Acad Sci U S A. 1991 Mar 15;88(6):2520-4. doi: 10.1073/pnas.88.6.2520.


The epidermal growth factor (EGF) receptor is both an activator and a target of growth factor-stimulated kinases involved in cellular signaling. Threonine-669 (T669) of the EGF receptor is phosphorylated in response to a wide variety of growth-modulating agents. MAP kinase is similarly phosphorylated as well as stimulated by growth activators, including EGF. To determine whether a MAP-type kinase is responsible for T669 kinase activity in EGF-stimulated 3T3-L1 cells, we partially purified and characterized the T669 peptide kinase. The results indicate that a MAP kinase phosphorylates the T669 peptide and raise the possibility that this enzyme may participate in a feedback loop, being activated by the EGF receptor and in turn phosphorylating the receptor.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Line
  • Chromatography, Affinity
  • Chromatography, Gel
  • Chromatography, Ion Exchange
  • Epidermal Growth Factor / pharmacology*
  • ErbB Receptors / metabolism*
  • Kinetics
  • Mice
  • Microtubule-Associated Proteins / metabolism
  • Phosphorylation
  • Protein-Tyrosine Kinases / isolation & purification
  • Protein-Tyrosine Kinases / metabolism*
  • Threonine


  • Microtubule-Associated Proteins
  • Threonine
  • Epidermal Growth Factor
  • ErbB Receptors
  • Protein-Tyrosine Kinases