Cloning and characterization of rat casein kinase 1 epsilon

Genes differentially expressed in the subjective day and night in the rat s uprachiasmatic nucleus (SCN) were surveyed by differential display. A gene homologous to human casein kinase 1 epsilon(CK1 epsilon) was isolated, whic h initially appeared to be expressed in the suprachiasmatic nucleus (SCN) i n a circadian manner. We here describe the cDNA cloning of the rat CK1 epsi lon and characterization of the protein products. The rCK1 epsilon is predo minantly expressed in the brain including the SCN, binds and phosphorylates mPer1, mPer2, and mPer3 in vitro, and translocates mPer1 and mPer3, but no t mPer2, to the cell nucleus depending on its kinase activity when coexpres sed with these Per proteins in COS-7 cells. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reser ved.