期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：9
页码：2451-2455
DOI：10.1073/pnas.69.9.2451
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The supernatant initiation factor from Artemia salina embryos promotes, besides the AUG-dependent binding of fMet-tRNAf, the poly(U)-dependent binding of N-acetylPhe-tRNA to 40S ribosomal subunits; the bound N-acylaminoacyl-tRNA reacts directly with puromycin upon addition of 60S subunits. Both the binding reaction and the synthesis of N-acylaminoacyl-puromycin occur in the absence of GTP or other ribonucleoside triphosphates. To a smaller extent, the factor also mediates the 40S ribosomal binding of Met-tRNAf and Phe-tRNA; in this case, the bound aminoacyl-tRNA is less reactive with puromycin. After the poly(U)- and supernatant factor-dependent binding of N-acetylPhe-tRNA to 40S subunits at low Mg2+ concentration, binding of a second aminoacyl-tRNA (Phe-tRNA), with ensuing formation of the first peptide bond, is dependent upon the addition of the 60S subunit, elongation factor EF-1, and GTP. Further growth of the polypeptide chain requires translocation and is, therefore, dependent upon the addition of elongation factor EF-2. As with the Escherichia coli system, once requirements for translation of the third codon have been met, no further additions are necessary for elongation of a peptide chain.
