FIG. 5.

Alteration of the nuclear coactivator binding interface inactivates selectively hRARα responsiveness to synthetic retinoids. (A) Three-dimensional modelling of the hRARα LBD showing the backbone of the polypeptide, helices 3, 4, and 12, and lysyl residues mentioned in the text (space-filling mode). The computer graphic was prepared with RasMol software. (B) Transcriptional activity of hRARα mutants K244A and K262A in the presence of natural and synthetic retinoids. HeLa cells were transfected with appropriate hRARα and hRXRα expression vectors and the TREpal-TATA Luc reporter gene (23) and stimulated with 1 μM retinoid. Luciferase activities represent induction values over the observed basal level (∼5,000 relative luciferase units in our conditions). Results represent the average values of six measurements ± standard error of the mean. Each assay was carried out six times.