Age-dependent decrease in the amount of eukaryotic initiation factor 2 in various rat tissues

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Abstract

Recent studies have suggested that the decline in protein synthesis that occurs in rat liver and brain during development and aging is associated with a decrease in the activity of eukaryotic initiation factor 2 (eIF-2). One way in which eIF-2 activity could be decreased in tissue extracts would be through a decrease in the activity of the GDP exchange factor, eIF-2B. In the present study, the activity of eIF-2B was measured in tissue extracts and was found to be less in older than in younger rats. Thus a decrease in eIF-2B activity could account for part of the decrease in protein synthesis that occurs during aging. Another way in which eIF-2 activity could be decreased would be through a decrease in amount of the protein. Therefore the amount of eIF-2 in various tissues was quantified by protein immunoblot analysis. We found that the amount of eIF-2 relative to total protein tended to fall with increasing age. Furthermore, eIF-2 content was directly proportional to the rate of protein synthesis in the tissues examined. Finally, slot-blot analysis of polyadenylated RNA revealed no significant change in the relative abundance of eIF-2α mRNA with age. The last-mentioned experiments suggest that the synthesis of eIF-2 may be regulated through changes in the efficiency of translation of eIF-2α mRNA rather than through changes in gene transcription.

Original languageEnglish (US)
Pages (from-to)263-268
Number of pages6
JournalBiochemical Journal
Volume286
Issue number1
DOIs
StatePublished - 1992

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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