Posttranslational photomodulation of circadian amplitude.

The transcription-translation feedback loops that form our current view of how the core mechanism of the clock operates is being challenged, as more and more posttranslational events are seen as essential to a full understanding of oscillator function. But in addition to phosphorylation, other processes may be involved. Here, a novel mechanism of posttranslational photomodulation of circadian amplitude is described that uniquely ties together light perception, protein stabilization, and proteolysis. In the process, the waveform of a core clock component is sharpened or "sculpted," resulting in appropriately high amplitude and proper phasing to obtain normal clock function.