MAP kinase kinase from rabbit skeletal muscle A novel dual specificity enzyme showing homology to yeast protein kinases involved in pheromone-dependent signal transduction

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MAP kinase kinase (MAPKK) was purified 30,000-fold to homogeneity from extracts of rabbit skeletal muscle and shown to be a monomeric protein of apparent molecular mass 44 kDa, MAPKK activated the 42 kDa isoform of MAP kinase by phosphorylation of Thr-183 and Tyr-185, and phosphorylated itself slowly on tyrosine, threonine and serine residues, establishing that it is a 'dual specificity' protein kinase. Peptide sequences from MAPKK were homologous to other protein serine/threonine kinases, especially to the subfamily that includes yeast protein kinase that lie upstream of yeast MAP kinase homologues in the pheromone-dependent mating pathways.

Original languageEnglish
Pages (from-to)183-189
Number of pages7
JournalFEBS Letters
Issue number2
Publication statusPublished - 17 Aug 1992



  • Mitogen-activated protein (MAP) kinase
  • Pheromone
  • Protein kinase
  • Signal transduction
  • Yeast

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