FIGURE 5.

CCA1 binds to the PHT4;1 promoter in EMSA. (A) Positions of the PHT4;1 promoter fragments (probes) and the CBS motifs (asterisks). Positions are relative to the translation start site (ATG). (B) EMSA with probe 1. (C) EMSA with probe 2 and probe 3. The probes were end-labeled with γ-³²P and incubated with purified recombinant CCA1-GST protein. For competition assays in (B), unlabeled fragments (probe 1 or PHT4;1-negative) at the indicated folds more than the input (isotope-labeled probe 1) were added to the binding reactions. The reactions were resolved on 6% native PAGE gels followed by gel drying and exposure to X-ray film.