title: Polypeptide chain initiation and stepwise elongation with Artemia ribosomes and factors.
abstract: The supernatant initiation factor from Artemia salina embryos promotes, besides the AUG-dependent binding of fMet-tRNA(f), 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-tRNA(f) 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 Mg(2+) 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.
mesh_terms: D000085:Acetates / Q000378:metabolism; D000818:Animals; D002247:Carbon Isotopes; D033364:Decapoda; D004590:Electrophoresis, Paper; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004926:Escherichia coli; D005561:Formates / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D008715:Methionine / Q000378:metabolism; D010452:Peptide Biosynthesis; D010441:Peptide Chain Elongation, Translational; D010442:Peptide Chain Initiation, Translational; D010649:Phenylalanine / Q000378:metabolism; D011119:Polynucleotides / Q000494:pharmacology; D011506:Proteins / Q000494:pharmacology; D011691:Puromycin / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D012265:Ribonucleotides / Q000494:pharmacology; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium; D014500:Uracil Nucleotides / Q000494:pharmacology
chemical_list: D000085:Acetates; D002247:Carbon Isotopes; D005561:Formates; D011119:Polynucleotides; D011506:Proteins; D012265:Ribonucleotides; D014500:Uracil Nucleotides; D014316:Tritium; D010649:Phenylalanine; D011691:Puromycin; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D008715:Methionine