Fig. 5. Quantification of the degree of nonsense suppression in the BSC783/4a transformants co-expressing N-terminally truncated and wild-type Sup35p. The various transformants were transformed with the PGK–lacZ fusion plasmids pUKC815 and pUKC817, and the levels of expressed β-galactosidase were used to determine the percentage nonsense suppression, as described in Materials and methods. The level of nonsense suppression in the pSUP transformant was taken as 100% and all other transformants were compared with that strain. For each transformant, four samples were assayed independently and the error bars represent standard deviation.