Codeword Recognition on 30 S Ribosomes

Interactions between sRNA and ribosomes have been studied in many laboratories (see Watson, 1964, for review). Gilbert (1963b) found that, after poly U-directed phenylalanine incorporation into protein in E. coli extracts, polyphenylalanine-sRNA is attached to 50 s subunits of 70 s ribosomes after dissociation in low Mg ++. Cannon, Krug, and Gilbert (1963) demonstrated that, without added messenger RNA, sRNA reversibly interacts with a site on 50 s subunits of 70 s ribosomes. In several laboratories poly U was found to direct with high specificity the attachment of phe-sRNA to ribo-somes, prior to peptide bond formation (Arlinghaus