Post‐translational timing mechanisms of the Drosophila circadian clock

Circadian clocks allow a temporal coordination and segregation of physiological, metabolic, and behavioural processes as well as their synchronization with the environmental cycles of day and night. Circadian regulation thereby provides a vital advantage, improving an organisms’ adaptation to its environment. The molecular clock can be synchronized with environmental cycles of day and night, but is able to maintain a self‐sustained molecular oscillation also in the absence of environmental stimuli. Interlocked transcriptional‐translational feedback loops were shown to form the basis of circadian clock function in all phyla from bacteria, fungi, plants, insects to humans. More recently post‐translational regulation was identified to be equally important, if not sufficient for molecular clock function and accurate timing of circadian transcription. Here we review recent insights into post‐translational timing mechanisms that control the circadian clock, with a particular focus on Drosophila . Analogous to transcriptional feedback regulation, circadian clock function in Drosophila appears to rely on inter‐connected post‐translational timers. Post‐translational regulation of clock proteins illustrates mechanisms that allow a precise temporal control of transcription factors in general and of circadian transcription in particular.