(A) In the Neurospora crassa circadian core clock oscillator FRH associates with FRQ and CK1a to form a repressor complex (FFC) that inhibits the positive-acting white-collar transcription factors (WC-1 and WC-2) which form the white-collar complex (WCC). Stoichiometries of the components are not represented in the schematic. FFC composition has been estimated as 1 FRH molecule: 2 FRQ molecules (Cheng et al, 2005; Hurley et al., 2013)), or 2 FRH molecules: 2 FRQ molecules (Lauinger et al, 2014). 