Initiation of mammalian protein synthesis. The multiple functions of the initiation factor eIF-3

Biochim Biophys Acta. 1979 Dec 17;565(2):305-14. doi: 10.1016/0005-2787(79)90207-7.


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.

MeSH terms

  • Animals
  • In Vitro Techniques
  • Magnesium / metabolism
  • Mice
  • Peptide Chain Initiation, Translational*
  • Peptide Initiation Factors / metabolism*
  • Phosphorus Radioisotopes
  • Proteins / metabolism*
  • Rabbits
  • Ribosomes / metabolism*


  • Peptide Initiation Factors
  • Phosphorus Radioisotopes
  • Proteins
  • Magnesium