Figure 1.

BBX21 binding of T/G-box in the HY5 promoter is independent on HY5. A, ChIP assays showing that BBX21 associated with the HY5 promoter in the presence and absence of HY5 in vivo. ChIP was performed with anti-myc monoclonal antibody, and the ChIP DNA was analyzed by real-time qPCR. The numbers represent the locations of the four HY5 promoter regions relative to the translation start site (referred to as position +1). Error bars represent sd of three technical replicates. B, EMSA assays showing BBX21 and HY5 independently bind to the subfragment of HY5 promoter (−349 to −252). TF, Trigger factor; FP, free probe. C, Schematic representation of various constructs used in the transient transfection assay in Arabidopsis protoplasts. Arrow after the 35S promoter indicates the transcriptional start site; −450 indicates the length of the HY5 promoter that was fused to the firefly luciferase to create the reporter construct. D, Bar graph showing activation by BBX21 and HY5 either alone or together on the ProHY5:LUC reporter. Error bars represent se (n = 3).