The RNA helicase FRH uses energy to control the CK1a protein in the daily clock of Neurospora crassa

The ATPase activity of FRH influences the hyperphosphorylation of the clock protein FRQ.

• FRQ undergoes hyperphosphorylation and eventual degradation over a circadian period.
• Timed hyperphosphorylation of FRQ is essential for maintaining the circadian clock's timing.
• CK1a-mediated hyperphosphorylation of FRQ is affected by the ATPase activity of FRH.
• The recruitment of CK1a to FRQ for phosphorylation is site-specific and requires activation upon binding.
• CK1a's affinity for FRQ decreases as FRQ becomes more hyperphosphorylated, indicating a potential inactivation of FRQ.

Simplified