Figure 4.

Δisy1 suppresses the relaxed fidelity of branch site recognition of prp16-302 and decreases accuracy of 3′-splice-site usage. Strains indicated in the legend were transformed with the ACT1-CUP1 reporter containing intron mutations. Serial dilutions of the strains were then grown on plates containing different mM concentrations of CuSO₄ for 5 d at 30°C. Bars indicate the highest millimolar concentration of copper tolerated by strains transformed with the indicated reporter. Tested concentrations are shown on the Y-axis. The reporter is depicted schematically at the bottom with the location of the different mutations indicated according to numbering of the actin intron.