Figure 2.

The regulation of the Gal1 and Met promoters. (A) Western blot analysis with anti-Myc antibodies. The regulation of the ADH (lanes 1–4), Met (lanes 5–7) and Gal1 (lanes 8–10) promoters was examined in three distinct media. The expression of myc-epitope Ras protein (myc–Ras; lanes 2–10) or Ras (lane 1) was detected with anti-Myc antibodies. Whole cell extract was derived from yeast transformants expressing the myc–Ras protein grown on either glucose (Glu)- or galactose (Gal)-containing medium in the presence or absence of methionine (GalΔM). The migration of myc–Ras and protein size markers are indicated. (B) Methionine-dependent growth of transformants expressing protein interacting pairs. Cdc25-2 transformants expressing the indicated protein pairs under the indicated promoter were grown on glucose medium at 24°C. The plate was replica plated onto galactose-containing plates in which methionine was either included or excluded from the medium. The plates were incubated at 36°C. Transformants expressing protein pairs under the control of Met and Gal1 promoters, respectively, are able to grow only on plates lacking methionine.