FIG. 3.

Replacement of threonine 42 of Ste50p with alanine abolishes its ability to suppress the STE11ΔSAM defect in mating. Yeast strain YCW466 (MATa STE11ΔSAM Δssk2 Δssk22) was transformed with the STE50 alleles indicated and tested for growth (left), for the ability to mate with tester strain DC17 (MATα his1) by selecting for diploids on minimal medium (second panel from left), and for the ability to grow on high-osmolarity medium containing 1.25 M sorbitol (third panel from left). Both the T42A and T42D alleles of Ste50p complement wild-type (WT) Ste50p function to allow strain YCW365 (Δste50 Δssk2 Δssk22) to grow on high-osmolarity medium containing 1.25 M sorbitol (right). Vec, control vector.