FIG. 7.

Enhancement of the RXR-SMRT interaction by the addition of RAR or T3R in vitro. Radiolabeled RXRα was synthesized by transcription and translation in vitro and tested for the ability to bind to a GST-SMRT (RID-1 plus RID-2) polypeptide (A and D), a GST-SMRT (RID-1) polypeptide (B and E), or a GST-SMRT (RID-2) polypeptide (C and F), each immobilized on glutathione-agarose. The incubations were performed in the presence (+) or absence (−) of various combinations of hormone, as indicated above each panel, and without further additions (None), in the presence of lysates of Sf9 cells infected with a nonrecombinant baculovirus (Sf-9), or in the presence of lysates of Sf9 cells infected with a baculovirus expressing high levels of either RARα (Sf-9 + RARα) (A to C) or T3Rα (Sf-9 + T3R) (D to F). The amount of radiolabeled RXR bound to a GST fusion polypeptide was visualized and quantified by PhosphorImager analysis and is presented numerically below each panel as a percentage of the total radiolabeled RXR (input) used in each binding reaction.