The accuracy of Qβ RNA translation: 1. Errors during the synthesis of Qβ proteins by intact Escherichia coli cells

The fidelity of Qβ RNA translation by intact Escherichia coli cells has been studied. After infection, host protein synthesis was eliminated by adding rifampicin and the radioactive, phage‐specified, proteins separated by one or two‐dimensional gel electrophoresis. Labelled histidine and tryptophan were incorporated into the phage coat protein, whose message does not specify these amino acids, at a frequency of 0.09–0.13 per molecule. Errors leading to a change in the pi of the coat protein occurred at a rate of 0.05 per molecule, while the coat protein UGA stop codon was misread 6.5% of the time. These error rates are similar to data in some recent publications but much higher than the canonical 3–4 × 10⁻⁴. They further provide a reference point in vivo to which the translation of the same message by E. coli extracts can be compared.