Fig. 3.

t-Darpp overexpression enhances PKA activity. (A) An ELISA-based CREB DNA binding activity assay was performed with SK.empty, SK.tDp and SK.tDp^T39A cells to assess the relative PKA activity in each cell line. Shown are the means (± S.D.) of three independent experiments, with normalization to the activity in SK.empty cells. Statistical significance was evaluated by one-way ANOVA corrected for multiple comparisons using Tukey’s post-hoc test. *p ≤0.05 compared to SK.empty. (B) Top, nFRET quantification of SK.empty, SK.tDp and SK.tDp^T39A cells transiently transfected with AKAR4 for 48 h, normalized to the average nFRET quantification in untreated SK.empty cells. Shown are the averages (± S.D.) from ≥30 cells imaged per cell line. Bottom, Representative confocal images of SK.empty, SK.tDp, and SK.tDp^T39A cells transiently transfected with AKAR4. The CFP and YFP channels were excited at 458 nm and 514 nm, respectively. The FRET channel was excited using CFP (458 nm) and captured using the emission range of YFP (535–590 nm).