(A) Intracellular pH changes as a function of environmental pH. Cells stressed in acidic media (pH 4.0, yellow) acidify, whereas cells stressed in media at the resting pH (7.5, blue) do not. (B) Inhibition of translation by glucose withdrawal does not depend on environmental pH. Incorporation of radiolabeled amino acids into total cellular proteins in counts per minute (cpm) as a function of time after a switch from medium at pH 4 with 2% glucose to the indicated media. (C) Same as A, but in glucose-free medium. (D) Induction of Ssa4 in cells able (yellow) or unable (blue) to acidify during heat shock. All measurements are of cells recovering in media containing 2% glucose. (E) Acidification promotes the transcriptional heat shock response (production of SSA4 mRNA) when cells are treated with the translation inhibitor cycloheximide (200 μg/mL) prior to heat stress. *, ; n.s., , Welch two-sample t-test. (F) Acidification promotes the heat shock response, and is required when cells are translationally inactive.