title: Control of single ribosome formation by an initiation factor for protein synthesis.
abstract: 30 and 50S ribosomal subunits, released from polysomes upon polypeptide chain termination, possess a high affinity for each other and readily form single ribosomes. Highly purified initiation factor F3(B), acting stoichiometrically, prevents the formation of single ribosomes without promoting their dissociation. These findings are interpreted in terms of a ribosome cycle in which a limiting amount of factor F3(B) controls the number of ribosomes active in protein synthesis, in response to metabolic changes in the cell, by regulating the flow of ribosomal subunits into polysomes or into a sidetrack pool of synthetically inactive single ribosomes. The reported apparent ribosome dissociation activity of F3(B) is explained.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001345:Autoradiography; D002499:Centrifugation, Density Gradient; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004926:Escherichia coli / Q000378:metabolism; D008274:Magnesium; D010452:Peptide Biosynthesis; D010442:Peptide Chain Initiation, Translational; D010759:Phosphorus Isotopes; D012270:Ribosomes / Q000032:analysis / Q000378:metabolism*; D014316:Tritium
chemical_list: D000900:Anti-Bacterial Agents; D010759:Phosphorus Isotopes; D014316:Tritium; D008274:Magnesium