Figure 1.

Yeast G protein/MAP kinase reporter cascade. In S. cerevisiae strains BY1142 and BY1173, activation of an episomally expressed mammalian GPCR stimulates nucleotide exchange on a chimeric Gα subunit. The newly free βγ moiety activates a MAP kinase cascade that leads to transcription of the HIS3 reporter gene, allowing growth on histidine-deficient medium.