Protein synthesis in rabbit reticulocytes XXII: A heat stable dialyzable factor (EIF-1*) modulates Met-tRNAf binding to EIF-1

A. Dasgupta, R. Roy, S. Palmieri, A. Das, R. Ralston, N. K. Gupta

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The peptide chain initiation factor EIF-1 forms a ternary complex, Met-tRNAf·EIF-1·GTP in the absence of Mg++ and the preformed complex is stable to Mg++. However, with homogeneous preparations of EIF-1, addition of Mg++ during the initial formation of the ternary complex strongly inhibits the complex formation. A heat stable dialyzable factor (EIF-1*) which mostly remains associated with the high molecular weight protein complex, EIF-2 (TDF) during purification of the peptide chain initiation factors, has been purified using a phenol extraction procedure. EIF-1* restores the Met-tRNAf binding activity of EIF-1 in the presence of 1 mM Mg++; in the presence of EIF-1*, Met-tRNAf binding by EIF-1 shows a sharp Mg++ optimum around 1 mM. EIF-1* is heat stable, alkali stable, dialyzable and pronase sensitive. The same EIF-1* preparation also strongly inhibits Met-tRNAf binding to EIF-1 in the absence of Mg++ and stimulates protein synthesis in a mRNA-dependent rabbit reticulocyte lysate system.

Original languageEnglish (US)
Pages (from-to)1019-1027
Number of pages9
JournalBiochemical and Biophysical Research Communications
Issue number3
StatePublished - Jun 14 1978

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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