Fig. 3. Confirmation of the association of TBL1 and HDAC3 with SMRT complex. (A) HDAC3 and TBL1 co-fractionated with SMRT in gel filtration chromatography. HeLa nuclear extract was fractionated by using a Superose 6 gel filtration column as in Figure 1 and the indicated fractions were analyzed by western blotting using the antibodies indicated. (B) SMRT protein in HeLa nuclear extracts was co-immunoprecipitated by antibodies specific for HDAC3 and TBL1, respectively; 5% input HeLa nuclear extract was used in lanes 1 and 3.