Casein kinase 1 isoform epsilon

Casein kinase I isoform epsilon or CK1ε, is an enzyme that is encoded by the CSNK1E gene in humans. It is the mammalian homolog of doubletime. CK1ε is a serine/threonine protein kinase and is very highly conserved; therefore, this kinase is very similar to other members of the casein kinase 1 family, of which there are seven mammalian isoforms (α, β, γ1, γ2, γ3, δ and ε). CK1ε is most similar to CK1δ in structure and function as the two enzymes maintain a high sequence similarity on their regulatory C-terminal and catalytic domains. This gene is a major component of the mammalian oscillator which controls cellular circadian rhythms. CK1ε has also been implicated in modulating various human health issues such as cancer, neurodegenerative diseases, and diabetes.

Discovery

CK1ε-tau Mutation

In hamsters, the CK1ε-tau mutation was first discovered by Michael Menaker and Martin Ralph in 1988 while studying a laboratory shipment of Syrian hamsters. They observed a hamster with an abnormal circadian period, and after breeding and further characterization, the two realized the mutation in hamsters conferred a shorter than normal free-running period. They attributed this phenotype to what they termed the "tau mutation", which was the first full description of a mammalian circadian mutant. This discovery provided a tool for other scientists to perform research on biological clocks and was an important early development in the field.