PCAF HAT domain interacts with each other in solution. A) MBP pulldown experiment using an MBP-PCAF HAT domain fusion. Purified MBP-PCAF fusion proteins were treated with 2 M NaCl to remove any bound maltose and mixed with new amylose beads and His-tagged PCAF fragments (lanes 4-6). The beads were then washed off unbound proteins and analyzed by 15% SDS-PAGE. Ten percent inputs of His-tagged PCAF fragments, MBP alone and MBP-PCAF fusion protein were used as loading controls (lanes 1-3). B) The presence of PCAF dimer state examined by co-immunoprecipitation. A plasmid that expresses Flag-PCAF was co-transfected with an empty vector pLV-nHA (lane 1) or HA-PCAF expression plasmid (lane 2). The expressions of Flag-or HA-PCAF were confirmed using 5% input shown at the bottom, while the Flag gel after wash was checked by western blotting as shown at the top.