title: Toward an understanding of the formylation of initiator tRNA methionine in prokaryotic protein synthesis. II. A two-state model for the 70S ribosome.
abstract: The 70S ribosomes can select the proper initiator tRNA between Met-tRNAfMet and fMet-tRNAfMet. Experiments on binding and on formation of aminoacylpuromycin, as a function of magnesium, potassium, or initiation factors, suggest a two-state equilibrium for 70S particles, involving a minor, active conformation and a major one which is not readily active. The formyl group would act as a specific trigger to select the active conformation. Experimental results are interpreted following this simple model and equilibrium parameters, together with kinetic constants of the peptidyltransferase activity, are presented.
mesh_terms: D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism; D007700:Kinetics; D008027:Light; D046911:Macromolecular Substances; D008274:Magnesium / Q000494:pharmacology; D008433:Mathematics; D008715:Methionine; D008954:Models, Biological; D010442:Peptide Chain Initiation, Translational / Q000187:drug effects; D011188:Potassium / Q000494:pharmacology; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000187:drug effects; D012343:RNA, Transfer / Q000378:metabolism*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D012542:Scattering, Radiation
chemical_list: D046911:Macromolecular Substances; D012343:RNA, Transfer; D008715:Methionine; D008274:Magnesium; D011188:Potassium