FIG. 7.

Identification of citric acid-induced proteins whose expression was dependent on deletion of the HOG1 gene. Protein expression in wild-type (WT) S. cerevisiae BY4741 and Δhog1 mutant in the presence or absence of 300 mM citric acid (CA), 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 Bmh1p (protein 23), Pdb1p (protein 24), Ura1p (protein 25), Fba1p (protein 26), YDR533cp (protein 27), Gnd1p (protein 28), and Car1p (protein 29) 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 Rps0bp (protein A). 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.