Role of eukaryotic initiation factor 5 in the formation of 80 S initiation complexes.
The function of eukaryotic initiation factor 5 (eIF-5) from rabbit reticulocyte lysate has been studied by sucrose gradient preparation of 40 S and 80 S initiation complexes. eIF-5 is required for transfer of initiator tRNA from 40 S preinitiation complexes to puromycin-reactive 80 S complexes. The transfer is dependent upon GTP hydrolysis and is associated with release of eIF-2 and eIF-3 from the 40 S subunit. The GTP-dependent loss of eIF-2 and eIF-3 is catalyzed by eIF-5 in the absence of 60 S subunits or when subunit joining is prevented by edeine, but not when GTP is replaced by GuoPP(NH)P. Unstable 40 S subunit . Met-tRNAf complexes generated by eIF-5 can form puromycin-reactive 80 S complexes when 60 S subunits are added in the absence of added GTP. In addition, kinetic evidence is presented that indicates GTP hydrolysis occurs prior to 80 S complex formation.
D000818:Animals; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D008715:Methionine; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors / Q000302:isolation & purification / Q000378:metabolism*; D011691:Puromycin; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism
D010448:Peptide Initiation Factors; D011691:Puromycin; D006160:Guanosine Triphosphate; D008715:Methionine