FIG. 2.

Gel shift assay to define the NR1 site as a DR4 motif and RXR binding. (A) Sequences of indicated NR1 mutants used as competitors for NR1 binding are compared to the wild-type NR1 (SP4 = wt). Spacer mutations are denoted by SP with numbers of bases. In MUT-SP, four bases of spacer are mutated. In addition to a random mutation in either the NR1a or NR1b site (NR1a mut and NR1b mut), these sites are mutated to create a perfect direct repeat with different orientations (PDR4, IR4, and ER4). The dots and hyphens indicate no change and deletions, respectively. The different nucleotides are shown in lowercase type. (B) Competition for NR1 binding was done with a 20-fold excess of indicated oligonucleotides. (C) Supershift assays were done by incubating preimmune IgG (1 μg) or indicated antibodies (1.5 μg) with liver nuclear extract from PB-treated mice. The results are representative of three independent experiments.