Analysis of posttranslational regulations in the Neurospora circadian clock

Posttranslational modification of circadian clock proteins by phosphorylation is an essential regulatory process in the control of eukaryotic circadian clocks. In the Neurospora circadian clock, the key clock protein FREQUENCY (FRQ) is progressively phosphorylated. The phosphorylation of FRQ is regulated by both kinases and phosphatases, and the phosphorylation is important for regulating FRQ stability and its function in the circadian negative feedback loop. The degradation of FRQ is mediated by the ubiquitin/proteasome pathway. This article discusses posttranslational regulations of the Neurospora clock and describes the methods used in the studies of FRQ phosphorylation, FRQ kinases and phosphatases, and FRQ degradation.