title: Stimulation of enzymatic phe-tRNA binding to mammalian ribosomes by thallium ions at concentrations blocking other ribosomal functions.
abstract: Thallium acetate (TIOAc) effectively stimulates poly(U)-directed Phe-tRNA binding to mouse ascitic tumour ribosomes under conditions when other ribosomal functions are completely blocked. The TI+ optimum is about 200 mM. The reaction is stimulated by EF-1, but not significantly by GTP. EF-1-dependent ribosomal GTPase is inhibited by T1+. The isolated Phe-tRNA . ribosome complex is relatively stable. The bound Phe-tRNA does not react with puromycin in the presence of 175 mM KCl. The complex formed in the presence of 90-100 mM TlOAc can, after isolation, be directly utilized for polyphenylalanine synthesis. The complex formed at 200 mM TlOAc is less active, apparently because of damage to the 60-S subunits. TlOAc at low concentrations (8 mM) stimulates K+ -containing poly(U)-translating systems, probably by stabilizing the translation complex.
mesh_terms: D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D001665:Binding Sites; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000378:metabolism; D051379:Mice; D010452:Peptide Biosynthesis; D010445:Peptide Elongation Factors; D010649:Phenylalanine / Q000378:metabolism*; D011072:Poly U / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D012343:RNA, Transfer / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D051381:Rats; D012270:Ribosomes / Q000378:metabolism*; D013793:Thallium / Q000494:pharmacology*
chemical_list: D010445:Peptide Elongation Factors; D012346:RNA, Transfer, Amino Acyl; D011072:Poly U; D010649:Phenylalanine; D000841:Anisomycin; D012343:RNA, Transfer; D013793:Thallium; D020963:GTP Phosphohydrolase-Linked Elongation Factors