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 RIS Download
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