Fig. 7. Overexpression of UPC2, ECM22, or both, causes a vacuolar defect. High-copy-number plasmids carrying either UPC2, ECM22 or no insert were used to transform the MOT3⁺ strain FY2066 to either Ura⁺, Leu⁺ or Ura⁺ Leu⁺, respectively. Transformants were selectively grown and then stained with FM4-64 (see Materials and methods). The percentage of plasmid-containing cells that had the vacuolar phenotype shown above is as follows: ECM22, 71% class B; UPC2, 70% class B; EMC22 and UPC2, 75% class B; the plasmid control, 78% class A.