Figure 3.

PXR/RXR heterodimers bind to IR0 elements. Shown are electrophoretic mobility-shift assays (EMSAs). Each reaction mixture contained reticulocyte lysate programmed to synthesize hPXR and/or hRXRα along with a ³²P-labeled oligonucleotide encoding a single copy of the indicated PXR response element. Arrowheads indicate labeled DNA-bound PXR/RXR. Free probes are indicated with asterisks. In B, all reaction mixtures contained ³²P-labeled rat STD IR0 probe along with increasing amounts (0.5×, 5×, 50×) of unlabeled oligonucleotide harboring the competitive response element. Note that both IR0 and DR3 competitor probes prevent formation of the slower mobility complex to similar extents, whereas the IR0 mutant competitor does not.