Abstract
Casein kinase I (CKI) is a serine/threonine protein kinase that performs various functions in the cell, such as DNA repair, cell-cycle regulation, cytokinesis, vesicular trafficking, morphogenesis and circadian-rhythm regulation. CKI proteins contain a highly conserved catalytic domain at the N-terminus and a highly diverse regulatory domain that is responsible for substrate specificity at the C-terminus. In this study, CKI from rice (riceCKI) was overexpressed in Escherichia coli with an engineered C-terminal His tag. RiceCKI was then purified to homogeneity and crystallized at 293 K. X-ray diffraction data were collected to a resolution of 2.0 Å from a crystal belonging to the monoclinic space group C2, with unit-cell parameters a = 108.83, b = 69.60, c = 55.85 Å, β = 109.47°. The asymmetric unit was estimated to contain one monomer.