Fig. 3. Association of SU(VAR)3-9 with HDAC1. (A) HDAC activity assay using immunoprecipitated material from two independently prepared nuclear extracts (myc-NE1 and myc-NE2) or a partially purified fraction (fraction 26) from the tagged fly strain precipitated with an anti-c-myc antibody (9E10) or no antibody (mock). (B) Western blot of immunoprecipitated material from (A) probed either with anti-HDAC1 (top panel), anti-HDAC3 antibodies (bottom panel, lanes 1–3) or anti-c-myc antibody (9E10) (bottom panel, lanes 5–6); the asterisk indicates the light chain of the antibody used for immunoprecipitation. The input lane (lane 1) contains ∼30% of the material used for immunoprecipitations. (C) HIM and HDAC activity assays of recombinantly expressed HDAC1 (left panel) and SUV3-91 (right panel). (D) HIM activity with immunoprecipitates using an anti-HDAC1 antibody from a partially purified fraction (Figure 1B, fraction 26). (E) HIM activity assay using material immunoprecipitated with an anti-flag antibody. Immunoprecipitates were purified from Drosophila control cells (SL-2) or cells stably expressing flag-tagged HDAC1 (fHDAC1).