Regulation of protein-synthesis elongation-factor-2 kinase by cAMP in adipocytes

TA Diggle*, NT Redpath, KJ Heesom, RM Denton

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

51 Citations (Scopus)

Abstract

Treatment of primary rat epididymal adipocytes or 3T3-L1 adipocytes with various agents which increase cAMP led to the phosphorylation of eukaryotic translation elongation factor-2 (eEF-2). The increase in eEF-2 phosphorylation was a consequence of the activation of eEF-2 kinase (eEF-2K), which is a Ca2+/calmodulin-dependent kinase. eEF-2K was shown to be essentially inactive at less than 0.1 mu M free Ca2+ when measured in cell-free extracts. Treatment of adipocytes with isoproterenol induced Ca2+-independent eEF-2K activity, and an 8-10-fold activation of eEF-2K was observed at Ca2+ concentrations of less than 0.1 mu M. Increased cAMP in 3T3-L1 adipocytes led to the inhibition of total protein synthesis and decreased the rate of polypeptide-chain elongation. We also show that the phosphorylation of eEF-2 and the activity of eEF-2K are insulin-regulated in adipocytes, These results demonstrate a novel mechanism for the control of protein synthesis by hormones which act by increasing cytoplasmic cAMP.

Original languageEnglish
Pages (from-to)525-529
Number of pages5
JournalBiochemical Journal
Volume336
Publication statusPublished - 15 Dec 1998

Keywords

  • insulin
  • protein kinase A
  • protein phosphorylation
  • translation
  • FACTOR-II KINASE
  • FAT-CELLS
  • PHOSPHORYLATION SITES
  • ADRENERGIC AGONISTS
  • CYCLIC-AMP
  • PHAS-I
  • INSULIN
  • ACTIVATION
  • IDENTIFICATION
  • TRANSLATION

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