An alpha subunit-deficient form of eukaryotic protein synthesis initiation factor eIF-2 from rabbit reticulocyte lysate and its activity in ternary complex formation.
Eukaryotic protein synthesis initiation factor eIF-2 is usually isolated as a heterotrimer (alphabeta gamma). By use of Sephacryl S-300 fractionation an alpha subunit-deficient form of eIF-2 was identified in impure preparations from rabbit reticulocyte lysate and it appeared in these preparations to be still active in formation of the ternary complex (eIF-2.GTP.Met-tRNAi). Subsequently alpha subunit-deficient eIF-2 was further purified and this appeared to have retained ternary complex forming activity. Together with a suggested lack of involvement of the beta subunit this implies that the alpha subunit was not required for activity and the gamma subunit bound both GTP and Met-tRNAi in formation of the ternary complex. The identification and study of alpha subunit-deficient eIF-2 thus elucidated the involvement of the subunits in binding of GTP and Met-tRNAi to produce the ternary complex in polypeptide chain initiation.
Mouat
M F
MF
Department of Biochemistry, University of the Witwatersrand, Johannesburg, South Africa.
Manchester
K
K
D000818:Animals; D002474:Cell-Free System; D002848:Chromatography, DEAE-Cellulose; D015852:Eukaryotic Initiation Factor-2 / Q000172:deficiency* / Q000378:metabolism*; D046911:Macromolecular Substances; D011817:Rabbits; D012156:Reticulocytes / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry; D013347:Subcellular Fractions / Q000737:chemistry
D015852:Eukaryotic Initiation Factor-2; D046911:Macromolecular Substances