Figure 7.

Sum1 was a general repressor of mating-type-specific genes. (A) Patch mating assays (using only the MATa tester) were performed on MATα, MATα sum1Δ, matα1Δ, matα1Δ sum1Δ, and matα1Δ sum1Δ hmlΔ strains in both S. bayanus and S. cerevisiae (W303). (B) Patch mating assays were performed on S. bayanus sum1Δ, mcm1Δ, and sum1Δ mcm1Δ strains of the indicated mating types. (C) Expression of α-specific genes in cells of indicated genotypes was assayed by quantitative RT–PCR (WT, wild type). Expression of STE3 is reduced 10-fold in mcm1Δ cells (columns 3 and 7) compared with wild-type a cells (column 1). It should be noted that ACT1 (actin) RNA levels in mcm1Δ mutant cells were reduced twofold, causing the normalized expression values for sum1Δ mcm1Δ cells to be inflated. (D) Expression of α-specific genes in cells of indicated genotypes was assayed by quantitative RT–PCR (WT, wild type).