Open AccessStimulation of Enzymatic Phe‐tRNA Binding to Mammalian Ribosomes by Thallium Ions at Concentrations Blocking Other Ribosomal Functions
Author(s) -
HULTIN Tore,
NÄSLUND Per H.
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12431.x
Subject(s) - puromycin , ribosome , ribosomal rna , enzyme , transfer rna , gtpase , gtp' , biochemistry , chemistry , protein biosynthesis , biophysics , stereochemistry , biology , rna , gene
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 Tl + 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 Tl + . 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 system, probably by stabilizing the translation complex.