Tubulin regulatory sequences drive expression of a dicistronic transcript that encodes two open reading frames, each separated by a self-cleaving P2A sequence (this results in separate translation of each protein). The first ORF encodes Scer\GAL3 tagged with a nuclear localization signal, and the second ORF encodes Scer\GAL80 containing a G310D amino acid substitution (this results in a protein that can interact normally with Scer\GAL3 but is defective in binding to GAL4) and tagged at the C-terminal end with GFP. In the absence of galactose, a diffuse fluorescent signal is seen (as the GFP-tagged GAL80(G310D) protein is free to shuttle in and out of the nucleus). In the presence of galactose, the GFP-tagged GAL80(G310D) protein is sequestered by the nuclear Scer\GAL3 protein, resulting in a quantifiable increase in nuclear fluorescence intensity.