FIG. 4.

Gal4 occupies the sites in ACC1 ORF. (A) The principle of the plasmid titration assay. There is one single weak UAS_GAL in the promoter of MEL1 (α-Gal gene). The expression of MEL1 reflects the available Gal4. When Gal4 binding sites are introduced by a multicopy plasmid, a decreased level of Gal4 will result in a lower level of MEL1. (B) Sc18 cells transformed with Yep351, YEP351-Gal1-10 promoter, and YEP351-ACC1. There are four Gal4 binding sites in the promoter of GAL1-10. The average copy number was determined by Southern blot.