Fig. 6. Mapping of repression domain of chick Pcl2 and inhibition of the mouse Shh promoter activities by chick Pcl2. (A) P19 cells were transfected with the reporter plasmid, pG5tkCAT, and the constructs indicated, and CAT (chloramphenicol acetyltransferase) activities were assayed. The N-domain of chick Pcl2, which covers the PHD fingers, represses about a third of the promoter activities, while the PHD domain suppresses the promoter activities to a half. C-terminal domain of chick Pcl2 exhibits similar effect to the controls on the promoter activities. (B) The 3 kb mouse Shh upstream region drives the expression of the CAT reporter gene in P19 cells (lane 1). The promoter activities are suppressed by co-expression of chick Pcl2 (lane 2) but not the PHD fingers (lane 3). Lanes 4-6 show the TK promoter activities that are not suppressed by co-expression of either chick Pcl2 (lane 5) or the PHD domain (lane 6), when compared with controls (lane 4). Data shown here represent at least three independent experiments.