This event signals the cells to terminate per and tim transcription. Around dawn, TIM is rapidly degraded and PER is released from the complex. Per and tim transcription commences once again, by midday. Recent studies suggest both, CRY and visual input regulate the main clock responsible for behavior in Drosophila. In plants, the circadian clock controls processes like photosynthesis, flowering and the passage of seasons.
Photosynthesis progresses optimally during the day.
Both Lhc transcription and LHC protein synthesis occur during the day peaking around noon. Another gene, the toc-1 gene has been identified in Arabidopsis as a component of the clock. Mutation in this gene affects several circadian outputs. A number of DNA-binding proteins bound to these sequences. One of them, a myb-like transcription factor CCA1 oscillates in a circadian fashion.