Transfer-RNA, magnesium and the formation of ternary complexes by eukaryotic initiation factor eIF-2.
The likely concentrations of free magnesium ions in assay systems measuring ternary complex formation with the eukaryotic initiation factor eIF-2 and the exchange of bound GDP have been calculated. Contrary to the suggestion of Roy et al. (Biochem. Biophys. Res. Commun. 146, 114-120) amounts of added tRNA are unlikely to sequester sufficient magnesium ions to affect significantly their role in the assays. There seems little correlation between methionyl-tRNA added and the extent of ternary complex formation in published data other than that expected from mass action. In vivo the concentration of methionyl-tRNA is probably greater than or equal to that of eIF-2 which is shown to be necessary for efficient functioning of the initiation factor.
Manchester
K L
KL
Department of Biochemistry, University of the Witwatersrand, Johannesburg, South Africa.
D055598:Chemical Phenomena; D002621:Chemistry; D015852:Eukaryotic Initiation Factor-2; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000032:analysis / Q000378:metabolism; D008274:Magnesium / Q000032:analysis / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000032:analysis / Q000378:metabolism*; D011506:Proteins / Q000032:analysis / Q000378:metabolism*; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism*; D012358:RNA, Transfer, Met / Q000032:analysis / Q000378:metabolism*
D015852:Eukaryotic Initiation Factor-2; D010448:Peptide Initiation Factors; D011506:Proteins; D012345:RNA, Transfer, Amino Acid-Specific; D012358:RNA, Transfer, Met; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D008274:Magnesium