title: Ethionine and the phosphorylation of ribosomal protein S6.
abstract: Ribosome phosphorylation was studied by monitoring the phosphorylation state of small subunit protein S6 as visualized on two-dimensional electrophoretograms of ribosomal proteins isolated from rat liver. No phosphorylation of S6 was observed under conditions of ethionine-induced inhibition of protein synthesis. Moderate phosphorylation, detected as the appearance of S6 and four or five phosphorylated derivatives, was observed in saline-treated animals. Reversal of ethionine-induced inhibition of protein synthesis by treatment with adenine led to extensive phosphorylation of S6. A model for protein synthesis which includes requisite phosphorylation of ribosomes during initiation is proposed. Cyclic adenosine 3':5'-monophosphate concentration was significantly elevated in liver of both ethionine- and ethionine plus adenine-treated rats, relative to that of saline-treated animals.
mesh_terms: D000225:Adenine / Q000494:pharmacology; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D005001:Ethionine / Q000494:pharmacology*; D005260:Female; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D051381:Rats; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D010750:Phosphoproteins; D012269:Ribosomal Proteins; D000242:Cyclic AMP; D000225:Adenine; D005001:Ethionine