By studying families with sleep/wake disorders, Fu and Ptáček have shown that mutations that cause changes in the phosphorylation or acylation of the PER2 protein are responsible for regulating circadian rhythms.



In Part 2 of the talk, Dr. Fu explains that studies of families with sleep disorders have shown that post-translational modifications of the PER2 protein are involved in regulating circadian rhythms. Casein kinase 1 phosphorylates PER2 and mutations in either CK1 or specific serine residues in PER2 result in an advanced sleep phase phenotype. O-GlcNAcylation of PER2 also participates in regulating circadian rhythms because O-GlcNAcylation blocks the sites usually phosphorylated by CK1.