Identification of substrates and regulators of the mitogen-activated protein kinase ERK5 using chimeric protein kinases

Jessie M. English, Gray Pearson, Richard Baer, Melanie H. Cobb

Research output: Contribution to journalArticlepeer-review

130 Scopus citations

Abstract

Extracellular signal-regulated protein kinase 5 (ERK5) is a recently discovered orphan mitogen-activated protein kinase for which no substrates or strong activators have been described. Two ERK5 chimeras were created as a novel approach to discover its substrates and upstream regulators. One chimeric protein contained the N-terminal domain of the ERK5 catalytic core (subdomains I-IV) and the C-terminal domain of the ERK2 catalytic core (subdomains V-XI). This chimera was highly responsive to stimuli that regulate ERK2 in vitro and in cells. A second chimeric protein consisted of the N-terminal domain of ERK2 (subdomains I-IV) and the C-terminal domain of the ERK5 catalytic core (subdomains V-XI). This chimera was activated in bacteria by coexpression with a constitutively active mutant of MEK1. Using the activated chimera, we identified three in vitro substrates of ERK5. Assaying ERK5 activity in immune complexes with one of these substrates, c- Myc, we determined that the ERK5 catalytic domain is activated by V12 H- Ras and to a lesser extent by phorbol ester but not by constitutively active mutants of Raf-1. Thus, ERK5 is a target of a novel Ras effector pathway that may communicate with c-Myc.

Original languageEnglish (US)
Pages (from-to)3854-3860
Number of pages7
JournalJournal of Biological Chemistry
Volume273
Issue number7
DOIs
StatePublished - Feb 13 1998

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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