The N-terminal ERK-binding site of MEK1 is required for efficient feedback phosphorylation by ERK2 in vitro and ERK activation in vivo

Bing E. Xu, Julie L. Wilsbacher, Tandi Collisson, Melanie H. Cobb

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90 Scopus citations


An ERK2-binding site at the N terminus of MEK1 was reported to mediate their stable association. We examined the importance of this binding site in the feedback phosphorylation of MEK1 on Thr292 and Thr386 by ERK2, the phosphorylation and activation of ERK2 by MEK1, and the interaction of MEK1 with ERK2 and Raf-1. Deletion of the binding site from MEK1 reduced its phosphorylation by ERK2, but had no effect on its phosphorylation by p21- activated protein kinase-1 (PAK1). A MEK1 N-terminal peptide containing the binding site inhibited MEK1 phosphorylation by ERK2. However, it did not affect MEK1 phosphorylation by p21-activated protein kinase or myelin basic protein phosphorylation by ERK2. Deletion of the N-terminal ERK-binding domain of MEK1 also reduced its ability to phosphorylate ERK2 in vitro, to co-immunoprecipitate with ERK2, and to stimulate ERK2 activation in transfected cells, but it did not alter the association with endogenous Raf- 1. Using ERK2-p38 chimeras and an ERK2 deletion mutant, a MEK1-binding site of ERK2 was localized to its N terminus.

Original languageEnglish (US)
Pages (from-to)34029-34035
Number of pages7
JournalJournal of Biological Chemistry
Issue number48
StatePublished - Nov 26 1999


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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