Fig. 1.

RXRα interacts with RFC3 in a ligand- and LXXLL motif-dependent manner. A, 9-Cis-RA- and rexinoid-activated human RXRα LBD interacts with hRFC3. The 293T cells were transfected with Gal4-thymidine kinase luciferase (Gal4-Tk-Luc) reporter vector (200 ng), Gal4-hRXRα-LBD (20 ng), VP16-hRFC3 (200 ng), VP16-hSRC1-C (200 ng), and LacZ expression vectors (pRSV-β-gal, 200 ng). After 24 h of transfection, the cells were incubated in the presence of the indicated ligands for 18 h. All cells were lysed, and the luciferase activities were measured and normalized against the LacZ expression as an internal control. Values are the average of three independent assays (mean ± sd), which were normalized to the control sample transfected with Gal4-hRXRα-LBD and VP16-hRFC3, and treated with DMSO instead of ligands. B, LXXLL motifs of RFC3 are critical for 9-cis-RA-dependent RXRα interaction. The hRFC3 fragments (hRFC-A, -B, and -C) and site-directed mutants (hRFC3–m1, -m2, and -m3) were fused to the VP16 gene and the constructs were transfected in 293T cells as described in A. Statistical changes were determined by the Student's t test (two-tailed) and are denoted as follows: *, P < 0.05; **, P < 0.01.