Crystallization and X‐ray diffraction

VRK1, 25 mg/mL in 20 mM Tris buffer (pH 7.5), 150 mM NaCl, and 1 mM DTT, was incubated with Adenylyl‐imidodiphosphate (AMP‐PNP) (Sigma‐Aldrich, USA), in a molar ratio of 1:6 and supplemented with 10 mM of MgCl₂, overnight at 4°C prior to crystallization using the hanging‐vapor diffusion method. The best crystals of VRK1–AMP‐PNP complex appeared in 27.5% w/v PEG 3350, 0.2 M of ammonium sulfate and 0.1 M of HEPES (pH 7.0) after 12–15 days at 18°C, with 2 μL of protein complex mixed with 1 μL of the reservoir solution equilibrated against 1 mL of reservoir solution. The crystals were cryo‐protected with 15% glycerol supplemented to the reservoir solution and diffraction data were collected at the National Synchrotron Radiation Research Center (Hsinchu, Taiwan) at 100 K on beamline, TPS05A using a MX300HS detector. Three datasets from a single crystal were collected.