FIG. 5.

Physical interaction of Rac1 and Ste20α assessed using the yeast two-hybrid system. (A) The cDNA sequences of the C. neoformans STE20α, RAC1, CDC42, and RAC1-G15V alleles were cloned into the two-hybrid vectors pGBT9 and pGAD424 and cotransformed in pair-wise combinations into the yeast strain PJ69-4A. One isolate transformed with the empty vectors was also tested as a control. Transformants were selected on synthetic medium lacking tryptophan and leucine (SD−Leu−Trp). These strains were assessed for growth on synthetic medium lacking tryptophan, leucine, and adenine (SD−Leu−Trp−Ade) and on synthetic medium lacking tryptophan, leucine, adenine, and histidine and containing 5 mM 3AT (SD−Leu−Trp−Ade−His+3AT). β-Galactosidase activity of four of these transformants was determined and expressed in Miller units (B). Data represent the means of triplicate samples; error bars indicate standard deviations.