PRR3, PRR5, PRR7 and PRR9 participate in the repressilator of a negative autoregulatory feedback loop that synchronizes to environmental inputs. The repressilator has a morning, evening, and night loop that are regulated in part by the pseudo-response regulator proteins' interactions with CCA1 and LHY. CCA1 and LHY exhibit peak binding to PRR9, PRR7, and PRR5 in the morning, evening, and night, respectively.