Extracellular signal-regulated kinases 2 autophosphorylates on a subset of peptides phosphorylated in intact cells in response to insulin and nerve growth factor: Analysis by peptide mapping

David J. Robbins, Melanie H. Cobb

Research output: Contribution to journalArticle

55 Scopus citations


The phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2) in response to insulin in Rat 1 HIRc B cells and in response to nerve growth factor (NGF) in PC 12 cells has been examined. ERK1 and ERK2 are phosphorylated on serine in the absence of the stimuli and additionally on tyrosine and threonine residues after exposure to NGF and insulin. NGF stimulates tyrosine phosphorylation of ERK1 more rapidly than threonine phosphorylation. Two-dimensional phosphopeptide maps of both ERK1 and ERK2 phosphorylated in intact cells treated with NGF or with insulin display the same three predominant phosphopeptides that comigrate when digests of ERK1 and ERK2 are mixed. As many as five additional phosphopeptides are detected under certain conditions. Autophosphorylated recombinant ERK2 also contains the three tryptic phosphopeptides found in ERKs labeled in intact cells. These experiments demonstrate that ERK1 and ERK2 are phosphorylated on related sites in response to two distinct extracellular signals. The data also support the possibility that autophosphorylation may be involved in the activation of the ERKs.

Original languageEnglish (US)
Pages (from-to)299-308
Number of pages10
JournalMolecular biology of the cell
Issue number3
StatePublished - Mar 1992
Externally publishedYes


ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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