Casein kinase 1

Discovery

By the early 1950s it was known from metabolic labeling studies using radioactive cyclic AMP ^[2].

Roles

Casein kinase activity was found to be present in most cell types and to be associated with multiple enzymes. The type 1 casein kinase family of related gene products are now given designations such as "casein kinase 1 alpha" and "casein kinase 1 epsilon". Casein kinase 1 alpha has been suggested to play a role in phosphorylation of Disheveled in the Wnt signaling pathway ^[3].

In humans there are three casein kinase 1 gamma enzymes. Working with the Xenopus system, Davidson et al screened for proteins that can regulate the Wnt signaling pathway by interacting with the Wnt receptor LRP^[4]. They reported that Xenopus casein kinase 1 gamma (CK1gamma) is associated with the cell membrane and binds to LRP. CK1gamma was found to be needed for Wnt signaling through LRP. is both necessary and sufficient to transduce LRP6 signalling in vertebrates and Drosophila cells. Wnt binding to LRP causes a rapid increase in phosphorylation of the cytoplasmic domain of LRP by CK1gamma. Davidson et al proposed that phosphorylation of LRP6 by CK1gamma promotes binding of Axin to LRP and activation of the Wnt signaling pathway^[4].

Casein kinase 1 epsilon is also important in the Wnt signaling pathway ^[5] and the Hedgehog signaling pathway ^[6].

Casein kinase 1 epsilon also acts in a molecular pathway that regulates the circadian rhythm ^[7].

See also

• Casein kinase 2 - a distinct protein kinase family

References