FIGURE 4.

DAX-1 competes with SRC-1 for LXRα transactivation. A, HepG2 cells were transfected using 200 ng of LXRE-Luc with indicated amounts of LXRα, SRC-1, and DAX-1 expression vectors. Cells were harvested 40 h after transfection, and lysates were utilized for luciferase and β-galactosidase assay. The results shown are the mean of β-galactosidase values from three independent experiments. Effects of DAX-1 and SRC-1 alone on the basal reporter activity are also shown. B, in vitro MBP competition assay. MBP-fused full-length LXRα (upper panel) or MBP-LXRαC (lower panel) bound to amylose beads was incubated with ³⁵S-labeled full-length HA-hDAX-1, in the presence of increasing amounts of cold methionine-labeled SRC-1 (1, 2, 4, or 8 μl). After washing, bound proteins were subjected to SDS-PAGE, and the amount of MBP-bound HA-DAX-1 was visualized via autoradiography.