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Structure of cDNAs encoding human eukaryotic initiation factor 3 subunits. Possible roles in RNA binding and macromolecular assembly.

The mammalian translation initiation factor 3 (eIF3), is a multiprotein complex of approximately 600 kDa that binds to the 40 S ribosome and promotes the binding of methionyl-tRNAi and mRNA. cDNAs encoding 5 of the 10 subunits, namely eIF3-p170, -p116, -p110, -p48, and -p36, have been isolated previously. Here we report the cloning and characterization of human cDNAs encoding the major RNA binding subunit, eIF3-p66, and two additional subunits, eIF3-p47 and eIF3-p40. Each of these proteins is present in immunoprecipitates formed with affinity-purified anti-eIF3-p170 antibodies. Human eIF3-p66 shares 64% sequence identity with a hypothetical Caenorhabditis elegans protein, presumably the p66 homolog. Deletion analyses of recombinant derivatives of eIF3-p66 show that the RNA-binding domain lies within an N-terminal 71-amino acid region rich in lysine and arginine. The N-terminal regions of human eIF3-p40 and eIF3-p47 are related to each other and to 17 other eukaryotic proteins, including murine Mov-34, a subunit of the 26 S proteasome. Phylogenetic analyses of the 19 related protein sequences, called the Mov-34 family, distinguish five major subgroups, where eIF3-p40, eIF3-p47, and Mov-34 are each found in a different subgroup. The subunit composition of eIF3 appears to be highly conserved in Drosophila melanogaster, C. elegans, and Arabidopsis thaliana, whereas only 5 homologs of the 10 subunits of mammalian eIF3 are encoded in S. cerevisiae.

Pubmed ID: 9341143


  • Asano K
  • Vornlocher HP
  • Richter-Cook NJ
  • Merrick WC
  • Hinnebusch AG
  • Hershey JW


The Journal of biological chemistry

Publication Data

October 24, 1997

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM22135
  • Agency: NIGMS NIH HHS, Id: GM26796
  • Agency: NIGMS NIH HHS, Id: GM36467

Mesh Terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Caenorhabditis elegans
  • Cloning, Molecular
  • Conserved Sequence
  • DNA, Complementary
  • DNA-Binding Proteins
  • Eukaryotic Initiation Factor-3
  • Evolution, Molecular
  • Female
  • HeLa Cells
  • Humans
  • Macromolecular Substances
  • Molecular Sequence Data
  • Molecular Weight
  • Multiprotein Complexes
  • Organ Specificity
  • Peptide Fragments
  • Peptide Initiation Factors
  • Phylogeny
  • Polymerase Chain Reaction
  • Pregnancy
  • Protein Biosynthesis
  • RNA, Messenger
  • Rabbits
  • Reticulocytes
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Transcription, Genetic