title: A specific inhibitor of polypeptide-chain initiation in Escherichia coli.
abstract: An inhibitor of polypeptide-chain initiation was isolated from E. coli cells. This protein inhibits formation of the 30S or 70S initiation complex with either fMet-tRNA(f) as initiator and AUG, MS2 RNA, or late T4 RNA as messenger, or acPhe-tRNA as initiator and poly(U) as messenger. Chain elongation, e.g., poly(U) translation at high Mg(2+) concentration, is not inhibited. The inhibitor is rendered ineffective when active aminoacylation of tRNA is taking place, e.g., during natural mRNA translation. This inhibitor is distinct from the so-called interference (i) factors, which interfere exclusively with the action of initiation factor 3. Since the new inhibitor can apparently be turned on and off, it may have a regulatory function in translation.
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D002250:Carbon Radioisotopes; D003090:Coliphages; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000032:analysis* / Q000166:cytology; D006868:Hydrolysis; D008715:Methionine; D010441:Peptide Chain Elongation, Translational / Q000187:drug effects; D010442:Peptide Chain Initiation, Translational / Q000187:drug effects*; D010649:Phenylalanine; D011072:Poly U / Q000378:metabolism; D011119:Polynucleotides / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D012343:RNA, Transfer / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D012270:Ribosomes / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D002250:Carbon Radioisotopes; D011119:Polynucleotides; D012367:RNA, Viral; D011072:Poly U; D010649:Phenylalanine; D012343:RNA, Transfer; D008715:Methionine