The rpL11B mutants affect translational fidelity 'Translational fidelity' is generically used to describe the accuracy of protein synthesis. A series of bicistronic reporter plasmids were used to quantitatively monitor the effects of the L11B mutants on four aspects of translational fidelity: À1 PRF, +1 PRF, suppression of a UAA nonsense codon and incorporation of a missense near-cognate amino acid. In JD1313 cells expressing wild-type RPL11B, À1 PRF directed by the L-A dsRNA viral signal was 6.07% ± 0.16%. This compares favorably with other 'wild-type' strains in our laboratory (normal range from 4% to 8% (20, 25) . The 51-4A mutant promoted increased À1 PRF (1.33 ± 0.06-fold relative to wild type), while 54-7A trended in the opposite direction (0.84 ± 0.03-fold relative to wild type) ( Figure 3 , and Table 1 ). Both these values were statistically significant and correlate well with the Killer À phenotypes. Y52Á, Y52N, Y52E and Y52H mutants also showed increased rates of -1 PRF, with statistically significant rates ranging from Y52H at 1.20-fold wild type to Y52E at 1.49-fold wild-type. Y52A, Y52S, Y52Q and Y52F all had wild-type rates of À1 PRF.