Figure 6.

BBX22 degradation depends in part on HY5 in the light but is independent of HY5 and HYH in the dark. A, BBX22 decreases in hy5 due to a lack of HY5-dependent transcriptional activation of BBX22. B, Northern-blot analysis was used to confirm the comparable expression of BBX22 transgene in Ler, hy5, and hy5hyh plants expressing 35S:BBX22 and grown in the dark (D) for 4 d or in 4-old etiolated seedlings illuminated with light for 24 h (L₂₄). The ethidium bromide-stained image was used to show the amount of total RNA samples loaded in each lane. C, Immunoblotting was used to detect BBX22 protein in the plant samples used in B. The detection of endogenous α-tubulin was performed as a loading control (TUB).