PP6 physically interacted with PIF3 and PIF4. LCI assays showed that FyPP1 interacted with PIF3 (A) and PIF4 (B) and that FyPP3 interacted with PIF3 (C) and PIF4 (D) in tobacco leaves. Empty vectors (cLUC and nLUC only) were used as negative controls. GST-FyPP3, but not GST, interacted with HIS-PIF3 (E), and MBP-FyPP3 interacted with GST-PIF4, but not GST (F). Immunoblotting analyses were conducted with anti-GST, anti-HIS, and anti-MBP antibodies. (G) PIF3-MYC interacted with YFP-FyPP3 in vivo. Total proteins were extracted from F3OE and PIF3-MYC/F3OE seedlings grown in the dark for 3 d. Anti-MYC antibodies were used for immunoprecipitation. Pellets were analyzed with anti-MYC and anti-GFP antibodies. (H) PIF4-MYC interacted with endogenous FyPPs in vivo. Total proteins were extracted from 3-d-old dark-grown seedlings of Col-0 and PIF4-4MYC. Anti-MYC antibodies were used for immunoprecipitation. Pellets were analyzed with anti-MYC and anti-FyPP antibodies. Asterisks denote cross-reacting bands.