The role of eIF-4C in protein synthesis initiation complex formation.
eIF-4C has a pronounced stimulatory effect on initiation complex formation with native 80-S ribosomes (80-Sn) as the only source of ribosomal subunits, but only a small effect when washed 40-S subunits are used. eIF-4C is accessary to eIF-3 in dissociating 80-Sn ribosomes. eIF-4C is present on 40-Sn but absent on 40-Sn dimers, which occur in preparations of native ribosomes and are as such inactive in protein synthesis. eIF-4C dissociates 40-Sn dimers into active monomers. These results can be explained by assuming that the presence of eIF-4C on 40-Sn prevents: (a) premature association with 60-S ribosomal subunits and (b) dimerisation, thus increasing the rate and extent of initiation complex formation.
D000818:Animals; D015977:Eukaryotic Initiation Factor-1; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D011817:Rabbits; D012269:Ribosomal Proteins / Q000096:biosynthesis; D012270:Ribosomes / Q000378:metabolism* / Q000648:ultrastructure; D014316:Tritium
D015977:Eukaryotic Initiation Factor-1; D046911:Macromolecular Substances; D010448:Peptide Initiation Factors; D012346:RNA, Transfer, Amino Acyl; D012269:Ribosomal Proteins; C026022:eukaryotic peptide initiation factor-1A; D014316:Tritium