Novel blue light receptors with an F-box: their direct control of the circadian clock and the flowering timing in Arabidopsis

Most plants sense their environmental changes such as photoperiod by using an endogenous circadian clock to regulate their developmental phases. The core oscillator of the clock has been reported to be composed of a negative feed back loop of transcription. Meanwhile, recent biochemical studies have been shedding light on the importance of post-translational regulations for the circadian mechanisms. ZEITLUPE (ZTL) family members are unique proteins which have three characteristic domains; a LIGHT, OXYGEN AND VOLTAGE domain, an F-box domain and six kelch repeats. Recently, two of the three family members, ZTL and FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 were reported to be novel types of blue light receptors which post-translationaly regulate the circadian clock and photoperiodic flowering, respectively. In this review, studies about ZTL family members making substantial progress are summarized and discussed.