FIG. 1.

Differential interactions between VDR and coactivators induced by vitamin D analogs in the yeast two-hybrid system. pGBT9(GAL4-DBD)-VDR(DEF) fusion protein and one of the indicated coactivators (SRC-1, TIF2, or AIB-1) or interacting proteins (RIP140, SUG1, or VAF-1) were expressed in yeast containing the lacZ gene controlled by the GAL4 enhancer. After incubation for 16 h in the presence of the 1α,25(OH)₂D₃ (10⁻⁸ M), 24R,25(OH)₂D₃ (10⁻⁸ M), or vitamin D analogs (10⁻⁸ M), as indicated, interaction of VDR with the coactivator or interacting protein was assessed by measuring β-galactosidase activity. Results are means ± standard deviations of three independent experiments.