FIG. 4.

dPER(Δ) is a very weak repressor of dCLK-dependent transactivation in S2 cells. (A) Shown are the average values from three independent experiments for relative Luc activity in the absence (−) or presence (+) of pMT-dClk-V5. In addition, some cells were also cotransfected with various amounts of pAct-dper(1-1224) or pAct-dper(Δ), as indicated. Luc activity in the absence of transfecting pMT-dClk-V5 was set to 1, and all other values were normalized. The following different amounts (ng) of pAct-dper(1-1224) or pAct-dper(Δ) were used: 1, 5, 10, 50, and 100. (B) S2 cells were transfected either singly with 50 ng of pMT-dClk-V5 (−) or in combination with 50, 100, or 500 ng of pAct-dper(1-1224) or pAct-dper(Δ). Cells were incubated with 500 μM CuSO₄ (final in the media) to induce ectopic expression of dCLK at 36 h after transfection and harvested 24 h later. Immunoblots were probed with antibodies against V5 to visualize dCLK-V5. Note that dCLK-V5 levels are very similar in cells expressing either dPER(1-1224) or dPER(Δ). (C) Shown are the average values from three independent experiments for relative Luc activity. Luc activity in the absence of pMT-dClk-V5 (−) was set to 1, and all other values were normalized. Two nanograms of pMT-Clk-V5 was used (+). pAct-dper(1-1224) and pAct-dper(Δ) were transfected singly or together in the presence (+) of pMT-Clk-V5. The following amounts of dper-containing plasmids were used in the transfections, as represented by the thicknesses of the black horizontal bars or triangles: 5 or 10 ng of pAct-dper(1-1224) and 5, 10, or 50 ng of pAct-dper(Δ).