Expression of sup45-n mutations in the presence of wild-type amount of eRF1 protein does not lead to readthrough. A. Two-hybrid interactions. Strain HF7C was co-transformed with pGADGH plasmids carrying different sup45-n mutations and pGBT9/SUP35 plasmid. The interactions were tested by the extent of resistance to 3-AT. Ten serial dilutions of yeast suspensions of the same density were used. Five independent transformants for each combination were tested. Representative results are shown. B. Western blot showing the expression of full-length eRF1+Gal4 and truncated eRF1+Gal4 proteins with predicted molecular mass in the same transformants as at (A).