FIGURE 1.

Determination of domains required for CHIP-Smad1 interaction. A, identification of the Smad1 binding domain on CHIP is shown. Glutathione beads immobilized with wild type GST-Smad1 were used to pull down CHIP mutants. Schematic diagrams on the top depict the CHIP proteins used, and a summary for their interaction with Smad1 is also listed on the right. The middle panel is the electrophoretic pattern of CHIP and Smad1 proteins after GST pulldown assays. The protein amounts of CHIP mutants used are shown at the bottom. The asterisk indicates the GST contaminant. CC, coiled-coil. B, shown is the determination of the Smad1 sequence critical for CHIP binding. The GST-mediated pulldown assays were carried out with various GST-tagged Smad1 fragments and CHIP-TPR. The panels are arranged as in panel A.