title: A supernatant factor involved in initiation complex formation with eukaryotic ribosomes.
abstract: Embryos of the brine shrimp, Artemia salina, were used in a study of polypeptide chain initiation in an in vitro system from a eukaryote. A protein, isolated from the high-speed supernatant, has been highly purified and shown to have properties that suggest it is the eukaryotic equivalent of the Escherichia coli initiation factor F(2): It promotes the AUG-dependent binding of fMet-tRNA (E. coli) to the Artemia 40S ribosomal subunit, but not to either the 60S or 80S species; the bound fMet-tRNA is placed in a site on the smaller subunit from which it reacts with puromycin upon addition of the 60S subunit; and the activity is sensitive to aurintricarboxylic acid and edeine, specific inhibitors of initiation. The factor, a basic protein of molecular weight about 100,000, is inactivated by N-ethylmaleimide, an SH-binding reagent, and is clearly distinct from the Artemia elongation factors, T(1) and T(2). In addition, the factor stimulates the poly(U)-dependent binding of Phe-tRNA (E. coli) to the Artemia 40S ribosomal subunit. This reaction, though similar to the fMet-tRNA-binding reaction, differs in that the bound Phe-tRNA is largely resistant to release by puromycin.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D002247:Carbon Isotopes; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology; D033364:Decapoda / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D006150:Guanine Nucleotides / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D010452:Peptide Biosynthesis; D010441:Peptide Chain Elongation, Translational / Q000187:drug effects; D010442:Peptide Chain Initiation, Translational / Q000187:drug effects; D010649:Phenylalanine / Q000378:metabolism; D011485:Protein Binding; D011691:Puromycin / Q000494:pharmacology; D012335:RNA, Ribosomal / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism; D014500:Uracil Nucleotides / Q000378:metabolism
chemical_list: D000227:Adenine Nucleotides; D002247:Carbon Isotopes; D003509:Cyclohexanecarboxylic Acids; D006150:Guanine Nucleotides; D012335:RNA, Ribosomal; D014500:Uracil Nucleotides; D010649:Phenylalanine; D011691:Puromycin; D012343:RNA, Transfer; D008715:Methionine; D005033:Ethylmaleimide