Figure 1.—

Induction of USA⁺ colonies by scrambled Ure2p PFDs. (A) Yeast strain YER135 expressing wild-type URE2 was transformed with either a plasmid containing the GAL1 promoter (vector) or expressing the indicated PFD from the GAL1 promoter. Yeast were grown in galactose/raffinose medium for 3 days. Cells (5 × 10⁵) were then plated onto USA medium to select for prion-containing cells. Colonies were counted after 5 days and photographed after 7. (B) Western blots of wild-type and scrambled Ure2 PFDs. Plasmids containing the GAL1 promoter (vector) or HA-tagged PFDs expressed from the GAL1 promoter were introduced into yeast strain YER135. Cells were grown in galactose medium and harvested in log phase. Cell lysates were analyzed by Western blot.