title: Biochemical research on oogenesis: protein synthesis by purified 42S particles from Xenopus laevis and Tinca tinca previtellogenic oocytes.
abstract: When incubated with ATP and a labeled amino acid, the 42S particles from early oocytes of Xenopus laevis and Tinca tinca incorporate radioactivity into tRNA and into a high molecular mass material which can be identified as protein. This incorporation is totally independent of ribosomes of cytosolic, mitochondrial or bacterial origin. The incorporated amino acids are linked to a broad spectrum of proteins by covalent bonds. Simple treatments such as incubation in buffer or addition of synthetic polyribonucleotides can inhibit the protein-labeling activity of the particles without affecting their tRNA aminoacylation activity. The former activity corresponds either to an amino acid polymerization reaction or to a protein-modifying reaction of a novel type. No involvement of mRNA in this process has been demonstrated. The alleged amino acid polymerization activity of the 42S particles could be a consequence of the conditions provided to aminoacyl tRNA by the tRNA-binding sites of the particles. These conditions are likely to allow the peptidyl transfer reaction to take place, although at a much lower rate than in the ribosome.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002412:Cations; D002499:Centrifugation, Density Gradient; D005260:Female; D005399:Fishes; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009865:Oocytes / Q000378:metabolism*; D009866:Oogenesis; D011131:Polyribonucleotides / Q000494:pharmacology; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012341:RNA, Ribosomal, 5S / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012260:Ribonucleases / Q000494:pharmacology; D012261:Ribonucleoproteins / Q000378:metabolism*; D014818:Vitellogenesis; D014982:Xenopus laevis
chemical_list: D000596:Amino Acids; D002412:Cations; D011131:Polyribonucleotides; D011500:Protein Synthesis Inhibitors; D012341:RNA, Ribosomal, 5S; D012346:RNA, Transfer, Amino Acyl; D012261:Ribonucleoproteins; D000255:Adenosine Triphosphate; D012343:RNA, Transfer; D012260:Ribonucleases