FIG. 4.

An Hsp90 mutation compromises ERK5 activity in yeast. (A) Growth at 37°C and caffeine resistance of P82a and T22I, strains expressing wild-type or T22I mutant Hsp90, and Slt2p-deficient forms of these strains (P82aslt2Δ and T22Islt2Δ) transformed with either the pG1-ERK5 expression vector (ERK5) or the control pG1 (E). (B) MET25 promoter-regulated MKK1-P386 expression exerts a dominant-negative effect in ERK5-expressing cells with the wild-type Hsp90 (P82aslt2Δ) but not those with T22I mutant Hsp90 (T22Islt2Δ). Growth (3 days, 30°C) was on DO medium either lacking only uracil or lacking uracil and methionine.