FIG. 8.

Identification of two citric acid-induced proteins whose expression is dependent on fully functional HOG1. Protein expression in wild-type (WT) S. cerevisiae BY4741 and Δhog1 mutant in the presence or absence of 300 mM citric acid (pH 3.5) is shown. Total soluble proteins were separated by IEF over the pH range 4 to 7. Proteins were prepared from untreated (control) cells (grown in ME medium [pH 3.5]) and cells grown in ME medium (pH 3.5) plus 300 mM citric acid (CA). The positions of Ssa1p (protein 8) and Eno2p (protein 13) are indicated. We also detected a protein whose expression was unaffected by exposure to citric acid alone but whose expression was repressed in the Δhog1 deletion mutant in the presence of citric acid. This protein was identified as Egd2p (protein B). Molecular masses (in kilodaltons) are shown on the y axis, and pI values are shown on the x axis. A representative result of two replicate experiments is shown.