Cyclic AMP-dependent protein kinase phosphorylates rabbit reticulocyte elongation factor-2 kinase and induces calcium-independent activity

N. T. Redpath, C. G. Proud

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Abstract

The catalytic subunit of cyclic AMP-dependent protein kinase (PKA) phosphorylated purified calcium/calmodulin-dependent eukaryotic elongation factor-2 (eEF-2) kinase, isolated from rabbit reticulocyte Iysates. It maximally incorporated about 1 mol of phosphate/mol of eEF-2 kinase. The K(m) of eEF-2 kinase for PKA was calculated to be 7μM. Phosphorylation of eEF-2 kinase by PKA induced calcium-independent activity which amounted to 40- 50 % of the total activity measured in the presence of calcium. Furthermore, the level of calcium-independent activity induced by phosphorylation by PKA was similar to that induced by the calcium-stimulated autophosphorylation of eEF-2 kinase. Phosphopeptide mapping of eEF-2 kinase labelled by autophosphorylation and by PKA revealed a number of common phosphopeptides. This suggests that PKA may phosphorylate the same site(s) which are phosphorylated autocatalytically and which are responsible for the induction of calcium-independent activity. The possible implications these findings have for the control of translation are discussed.

Original languageEnglish
Pages (from-to)31-34
Number of pages4
JournalBiochemical Journal
Volume293
Issue number1
DOIs
Publication statusPublished or Issued - 1993
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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