Open AccessPolypeptide Chain Initiation in Eukaryotes: Functional Identity of Supernatant Factor from Various Sources
Author(s) -
Michael Zasloff,
Severo Ochoa
Publication year - 1972
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.69.7.1796
Subject(s) - ribosome , reticulocyte , artemia salina , puromycin , biology , initiation factor , biochemistry , ribosomal rna , protein subunit , escherichia coli , gtp' , eukaryotic small ribosomal subunit , microbiology and biotechnology , protein biosynthesis , chemistry , enzyme , rna , organic chemistry , toxicity , gene
Eukaryotic cells contain polypeptide chain initiation factors that, like the prokaryotic initiation factor IF-2, promote the AUG-dependent binding of fMet-tRNAf to the small ribosomal subunit. The bound amino-acyl-tRNA is directly convertible to fMet-puromycin upon addition of 60S subunit. The reaction is sensitive to initiation inhibitors such as aurintricarboxylic acid and edeine but, unlike its prokaryotic counterpart, it does not require GTP. Factors that catalyze the binding and fMet-puromycin reactions with ribosomal subunits fromArtemia salina embryos are present in postribosomal supernatants ofArtemia , mouse fibroblasts (L cells), and rat liver, as well as in salt washes of rabbit reticulocyte ribosomes. However, whereas all three supernatant factors, likeEscherichia coli IF-2, are sensitive to SH-binding reagents, the reticulocyte factor is not. The rat liver andArtemia factors function indiscriminately withArtemia or rat liver ribosomes, but theArtemia factor andE. coli initiation factor IF-2 are not interchangeable.