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. Author manuscript; available in PMC: 2020 May 16.
Published in final edited form as: Mol Cell. 2019 Apr 3;74(4):771–784.e3. doi: 10.1016/j.molcel.2019.03.003

Figure 7.

Figure 7

Re-assessment of kinases and a phosphatase previously implicated in regulation of WCC activity, and a summary model for the role of phosphorylation in regulating WCC activity. A PKA and PP2A are not required for WCC circadian activity. WCC activity was monitored by frq C-box-luc in the Δpkac-1, Δpkac-2, and in the rgb-1RIP strain that is defective in PP2A activity on the WCC. B Working model for the role of phosphorylation in regulating WCC activity. In a circadian cycle, FRQ/FRH/CK1 promotes phosphorylation of key residues (red circles) on both WC-1 and WC-2 to repress WCC activity in the feedback loop of the core clock, and also induces phosphorylation near the ZnF region of WC-1 (purple circles) that acts to depress the circadian amplitude as an aid to enhance robustness of circadian outputs.