Differing effects of the protein phosphatase inhibitors okadaic acid and microcystin on translation in reticulocyte lysates

Nicholas T. Redpath, Christopher G. Proud

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16 Citations (Scopus)


The effects of the cyanobacterial toxin and protein phosphate inhibitor, microcystin, on translation in rabbit reticulocyte lysates have been studied. Microcystin inhibited translation with similar potency to the protein phosphatase inhibitor okadaic acid. Unlike low concentrations of okadaic acid, however, it inhibited both the initiation and elongation stages. This was demonstrated using EGTA to inhibit the phosphorylation and inactivation of elongation factor eEF-2. A method for detecting change in eEF-2 phosphorylation was developed. eEF-2 was found to exist as three different species: eEF-2 was largerly monophosphorylated in reticulocyte lysates under control conditions, the remainder being unphosphorylated. Okadaic acid and microcystin increased the level of the bisphosphorylated species. The implications of multiple phosphorylation of eEF-2 for the control of translation is discussed. Microcystin was also found to increase the phosphorylation of eIF-2α (and therefore to inhibit initiation) at lower concentrations than okadaic acid, suggesting that the major eIF-2α phosphatase in the reticulocyte lysate is phosphatase-1.

Original languageEnglish
Pages (from-to)36-41
Number of pages6
JournalBBA - Molecular Cell Research
Issue number1
Publication statusPublished or Issued - 7 Jun 1991
Externally publishedYes


  • Elongation factor-2
  • Initiation factor-2
  • Microcystin
  • Okadaic acid
  • Protein phosphorylation
  • Protein synthesis

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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