Identification of BBX proteins as rate-limiting cofactors of HY5.

As a source of both energy and environmental information, monitoring of incoming light is crucial for plants to optimize growth throughout development. Concordantly, the light signalling pathways in plants are highly integrated with numerous other regulatory pathways. One of these signal integrators is the basic leucine zipper domain (bZIP) transcription factor LONG HYPOCOTYL 5 (HY5), which has a key role as a positive regulator of light signalling in plants.