FIG. 3.
pbx1a associates with the corepressors NCoR and SMRT. (A) Transient-transfection assay of GAL4-pbx1a and GAL4-pbx1b polypeptides on a GAL4 thymidine kinase luciferase reporter plasmid in 293T cells. The activities of GAL4 DNA-binding domain and GAL4-pdx polypeptides are shown for comparison. A Western blot assay of nuclear extracts from transfected 293T cells with αGAL4 antiserum was done to show comparable expression levels of each GAL4 fusion construct. Asterisks indicate immunoreactive bands corresponding to each polypeptide. (B) GST pull-down assays of 35S-labeled NCoR and SMRT after incubation with GST, GST-pbx1a, or GST-pdx polypeptides in vitro. OP, 10% of input. (C) Carboxy-terminal domains of NCoR and SMRT associate with pbx1a. GST pull-down assay of 35S-labeled NCoR (top) and SMRT (bottom) polypeptides with GST or GST-pbx1a glutathione-Sepharose resins. Inclusive amino acid endpoints for each NCoR and SMRT polypeptide are shown.