Moe1 and spInt6, the fission yeast homologues of mammalian translation initiation factor 3 subunits p66 (eIF3d) and p48 (eIF3e), respectively, are required for stable association of eIF3 subunits

Amitabha Bandyopadhyay, Viswanathan Lakshmanan, Tomohiro Matsumoto, Eric C. Chang, Umadas Maitra

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The protein encoded by the fission yeast gene, moe1+ is the homologue of the p66/eIF3d subunit of mammalian translation initiation factor eIF3. In this study, we show that in fission yeast, Moe1 physically associates with eIF3 core subunits as well as with 40 S ribosomal particles as a constituent of the eIF3 protein complex that is similar in size to multisubunit mammalian eIF3. However, strains lacking moe1+ (Δmoe1) are viable and show no gross defects in translation initiation, although the rate of translation in the Δmoe1 cells is about 30-40% slower than wild-type cells. Mutant Δmoe1 cells are hypersensitive to caffeine and defective in spore formation. These phenotypes of Δmoe1 cells are similar to those reported previously for deletion of the fission yeast int6+ gene that encodes the fission yeast homologue of the p48/Int6/eIF3e subunit of mammalian eIF3. Further analysis of eIF3 subunits in Δmoe1 or Δint6 cells shows that in these deletion strains, while all the eIF3 subunits are bound to 40 S particles, dissociation of ribosome-bound eIF3 results in the loss of stable association between the eIF3 subunits. In contrast, eIF3 isolated from ribosomes of wild-type cells are associated with one another in a protein complex. These observations suggest that Moe1 and spInt6 are each required for stable association of eIF3 subunits in fission yeast.

Original languageEnglish (US)
Pages (from-to)2360-2367
Number of pages8
JournalJournal of Biological Chemistry
Issue number3
Publication statusPublished - Jan 18 2002


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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