Fig. 4.

FKF1 inhibits COP1 homo-dimerization in a light-dependent manner. a FKF1 requires light to interact with COP1 and inhibit COP1 dimerization. In the absence of FKF1, COP1 dimerization occurs in both light and dark conditions. In the presence of FKF1, FKF1 interacts with COP1 only under light in N. benthamiana. Two days after co-infiltration, tobacco leaves were harvested under light (L) and dark (D) in LD. b Light-dependent interaction between FKF1 and COP1 in 35S:FKF1 #18. The 10-day-old seedlings were harvested in the light period (L) and dark period (D) in LD. * indicates COP1 and ** indicates non-specific bands derived from an anti-COP1 antibody. FKF1 was detected by an anti-FKF1 antibody. c FKF1 inhibits COP1 dimerization light-dependently in yeast three-hybrid assays. The interactions were evaluated based on yeast cell survival (upper panel), and were further confirmed by β-galactosidase (β-Gal) activity (lower panel). Data are means ± s.d. of three samples. Met, methionine; −LWM, the absence of Leu/Trp/Met in the yeast media; −LWMH, the absence of Leu/Trp/Met/His; AD, activation domain; BD, binding domain; C, COP1; S, SPA1. − or + represent the presence or absence of protein expression, respectively. In FKF1, −/+ indicates the absence of FKF1 in the first and second panels due to the addition of 1 mM Met and the presence of FKF1 in the third and fourth panels because 1 mM Met was not added to the yeast media