Initiation of mammalian protein synthesis. The multiple functions of the initiation factor eIF-3.
The protein synthesis initiation factor eIF-3 (a multicomponent protein complex) was labelled with 32P by phosphorylation with a protein kinase present in a partially purified 'hemin-controlled repressor' preparation. The interaction of the labelled factor with the 40 S ribosomal subunit during the course of initiation was followed. It binds to the 40 S subunit in the absence of other initiation factors and inhibits the Mg2+-dependent reassociation of the 40 S with the 60 S ribosomal subunit. It stimulates the binding of the ternary complex (eIF-2, GTP, Met-tRNAf) to the 40 S subunit, and earlier work (Trachsel, H., Schreier, M.H., Erni, B. and Staehelin, T. (1977) J. Mol. Biol. 116, 745-767) also showed it to be essential for the subsequent binding of mRNA. The factor is released from the 40 S initiation complex during the 60 S subunit joining reaction.
D000818:Animals; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D051379:Mice; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D011506:Proteins / Q000378:metabolism*; D011817:Rabbits; D012270:Ribosomes / Q000378:metabolism*
D010448:Peptide Initiation Factors; D010761:Phosphorus Radioisotopes; D011506:Proteins; D008274:Magnesium