FIG. 5.

N-CoR corepressor binds and activates HDAC3. (a) Alignment of the SMRT DAD with homologous regions of the corepressors N-CoR and SMRTER. Residues conserved in at least two of the three proteins are shown on black background. (b) Myc-HDAC3 alone or mixed with either Flag-SMRT or Flag–N-CoR was immunoprecipitated with anti-Myc and subjected to HDAC assay. Immunoprecipitation of an unprogrammed transcription-translation mix was used as a control. (c) Immunoblot (IB) of HDAC3 complexes immunoprecipitated (IP) by anti-Myc. The upper panel was probed for SMRT or N-CoR (anti-Flag); the lower panel was probed for HDAC3 (anti-Myc). (d) Myc-HDAC3 alone or mixed with either MTA1 or Flag-SMRT was immunoprecipitated with anti-Myc and subjected to HDAC assay. (e) Immunoblot analysis of the Myc-HDAC3 immunoprecipitates in panel d. The upper panel was probed with anti-MTA1, the middle panel was probed for SMRT (anti-Flag), and the lower panel was probed for HDAC3 (anti-Myc). Five-percent inputs are shown on the left, and all proteins were produced by T7-coupled transcription-translation.