The effect of chlortetracycline on the transfer of leucine and ‘transfer’ ribonucleic acid to rat-liver ribosomes in vitro

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Abstract
Chlor-tetracycline apparently had no effect on the energy-dependent binding of "transfer" ribonucleic acid [RNA] labelled with [C14]uracil and [C14]cytosine to microsomes or ribosomes in cell-free systems from rat liver. Chlortetracycline strongly inhibited the transfer of [C14]leu-cine to a fraction of the ribosome which was insoluble in cold trichloro-acetic acid but was released by hot trichloroacetic acid. The transfer of leucine to this fraction was dependent on the presence of phosphoenol-pyruvate and the 105000 g supernatant. The observed radioactivity of ribosomal RNA labelled with [C14]ieucine varied considerably, depending on the method of extraction of RNA. Sucrose-density-gradient analysis of ribosomal RNA labelled with [C14]leucine indicated that all the radio-activity was in the 4 s fraction. The significance of these results is discussed in relation to the mode of action of chlortetracycline and current views on the "transfer" RNA-ribosome interaction.