Figure 4.

CLK repression is specific to KAY-α. Drosophila S₂R⁺ cells were transfected as indicated. A β-galactosidase-expressing plasmid was cotransfected to normalize transfection efficiency. The relative luciferase activity with Clk or VP16–cwo was set to 100 on the graph. A, CLK activation in the presence of different KAY isoforms. Neither KAY-β, KAY-γ, nor KAY–TRUNC can repress CLK activation of the tim promoter or the per E-box. B, KAY-β, KAY-γ, KAY–TRUNC, and KAY-α–BASICΔ are well expressed in S₂R⁺ cells. Cell lysates were immunoblotted with anti-KAY-main body antibody (left) or anti-KAY-α/TRUNC antibody (right). C, KAY-α does not repress the activation of the tim promoter by VP16–CWO.