Multipoint phosphorylation of the PERIOD 2 (PER2) protein is a critical step in determining the mammalian clock cycle. Previous studies have suggested that the phosphorylation of PER2 by casein kinase 1 (CK1) requires the initiation of an undiscovered protein kinase. CK1 is an essential circulatory protein that is highly conserved from algae to humans. These phosphorylation processes stabilize the PER2 and delay its degradation to extend the circadian clock cycle….