FIG. 5.

Pho2-DNA binding is required for cooperativity between Pho2 and Pho4 also at UASp2. The binding reaction and the gel shift assay were performed as described in Materials and Methods. A labeled 109-bp PCR-generated promoter fragment (−316 to −208) containing UASp2 and either the wild-type (wt) sequence or the combined M4+M5 mutation, shown schematically at the bottom, were used. The amounts of protein added to the assay mixture are listed in arbitrary units (for details, see the legend to Fig. 3). For the explanation of the arrow and the asterisks, see the legend to Fig. 3.