Eukaryotic initiation factor 2 from rat liver: no apparent function for the β-subunit in the formation of initiation complexes

David R. Colthurst, Christopher G. Proud

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Eukaryotic protein synthesis initiation factor 2 (eIF-2) from rat liver has been resolved into two subfractions by anion-exchange chromatography on DEAE-cellulose. One of these contained all three components (eIF-2α, eIF-2β, eIF-2γ) characteristic of mammalian eIF-2, whilst the other fraction contained only two. By a number of criteria these were shown to be eIF-2α and eIF-2γ. The absence of eIF-2β from this fraction was not due to its proteolytic degradation during purification since it was unaffected by the inclusion of a range of proteinase inhibitors in the isolation media. The properties of eIF-2 containing or lacking eIF-2β have been directly compared. It was found that eIF-2β was not required for the binding of guanine nucleotides to eIF-2 or for formation of ternary initiation complexes with GTP and the initiator tRNA. eIF-2 lacking eIF-2β was able to form 40 S initiation complexes and the presence of eIF-2β was also unnecessary for the stimulation of eIF-2 activity by the recycling factor, eIF-2B. Some of these findings are at variance with previous reports in which eIF-2β was removed proteolytically. The role of eIF-2β in the overall physiological function of eIF-2 remains to be elucidated.

Original languageEnglish
Pages (from-to)77-86
Number of pages10
JournalBBA - Gene Structure and Expression
Issue number1
Publication statusPublished or Issued - 16 Oct 1986
Externally publishedYes


  • Guanine nucleotide
  • Initiation factor
  • Protein synthesis
  • Translational control

ASJC Scopus subject areas

  • Structural Biology
  • Biophysics
  • Biochemistry
  • Genetics

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