Eukaryotic initiation factors-4E and -4F stimulate 5' cap-dependent as well as internal initiation of protein synthesis

G C Scheper, H O Voorma, A A Thomas

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Two mechanisms of initiation of protein synthesis are known. The 5' cap-dependent model requires the activity of cap-binding eukaryotic initiation factors (eIF)1-4E and -4F, inducing unwinding of mRNA secondary structures. The internal initiation model is 5' cap-independent and requires a ribosomal entry site formed by higher order structures of the mRNA. It has been proposed that this mechanism does not need eIF-4E and eIF-4F. We prepared bicistronic transcripts on which both mechanisms of initiation occur, allowing the determination of the initiation factor dependence of these two mechanisms simultaneously. The unwinding factors eIF-4A, eIF-4B, and eIF-4F were found to be necessary for 5' cap-dependent initiation as well as for internal initiation. Surprisingly, efficient translation of both cistrons on the bicistronic mRNA required eIF-4E. A model is presented in which assembly of eIF-4E into a functional eIF-4F complex is a prerequisite for both types of initiation.

Original languageEnglish
Pages (from-to)7269-74
Number of pages6
JournalJournal of Biological Chemistry
Volume267
Issue number11
Publication statusPublished - 15 Apr 1992

Keywords

  • Bacterial Proteins
  • Base Sequence
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli
  • Eukaryotic Initiation Factor-4E
  • Eukaryotic Initiation Factor-4F
  • Genes, Viral
  • Molecular Sequence Data
  • Mosaic Viruses
  • Nucleic Acid Conformation
  • Peptide Chain Initiation, Translational
  • Peptide Initiation Factors
  • Plasmids
  • RNA Caps
  • RNA, Messenger
  • Transcription, Genetic

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