Fig 4. G70N and Y66H substitutions in Ydj1 allow maintenance of the strong [PSI⁺] prion.

(A) Maintenance of Sc4 (strong) and Sc37 (weak) [PSI⁺] by Ydj1₁₃₄ suppressor variants in sis1-Δ strains. Equal number of cells were dropped on YPD and grown at 23˚C for 5 days for assessment of color development. Dashed line indicates different parts of the same plate where irrelevant strains were cropped out of the image. For both variants, a representative of the 10 candidates isolated from 5-FOA plates that were tested for [PSI⁺] maintenance; all showed similar color phenotype. Parent [PSI⁺] cells for each prion variant (parent) and cells cured of the prion by growth in the presence of GdnHCL (cured). (B) For analysis of [PSI⁺], cell lysates were prepared, resolved by SDD-AGE and subjected to immunoblotting using Sup35-specific antibodies.