Casein kinase 1 delta (CK1δ) and its closest homologue CK1ε are key regulators
of diverse cellular growth and survival processes such as Wnt signaling, DNA
repair, and circadian rhythms. We report three crystal structures of the kinase
domain of human CK1δ, one apo and two complexed with a potent and selective
CK1δ/ε inhibitor PF670462 in two different crystal forms. These structures
provide a molecular basis for the strong and specific inhibitor interactions and
suggest clues for further development of CK1δ/ε inhibitors.