title: Actinomycin D inhibits hemoglobin synthesis in rabbit reticulocyte lysates and binds to a 15 S cytoplasmic particle involved in the initiation step of translation.
abstract: Actinomycin D inhibits hemoglobin synthesis in rabbit reticulocyte lysates by affecting initiation of globin polypeptide chains. To obtain information on the distribution of actinomycin-sensitive structures among the components of the translation machinery, a reticulocyte lysate is incubated with [3H]actinomycin. The tritium label is found associated with ribosomes actively engaged in protein synthesis and with a 15 S cytoplasmic particle. During cell-free incubation or when initiation is inhibited by aurintricarboxylic acid, the labeling of the 15 S particles increases, suggesting that they are relased from ribosomes into the cytoplasm and play a role in the initiation process. The 15 S cytoplasmic particles contain a DNAase-sensitive component, probably complexed with ribonucleic acids and proteins. A possible role of these DNA-containing particles in the initiation step of translation is discussed.
mesh_terms: D001312:Aurintricarboxylic Acid / Q000494:pharmacology; D002474:Cell-Free System; D003593:Cytoplasm / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology*; D003851:Deoxyribonucleases / Q000378:metabolism; D006454:Hemoglobins / Q000096:biosynthesis*; D007930:Leucine / Q000378:metabolism; D010452:Peptide Biosynthesis; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors; D010649:Phenylalanine / Q000378:metabolism; D011485:Protein Binding; D012156:Reticulocytes / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism
chemical_list: D006454:Hemoglobins; D010448:Peptide Initiation Factors; D003609:Dactinomycin; D001312:Aurintricarboxylic Acid; D010649:Phenylalanine; D003851:Deoxyribonucleases; D007930:Leucine