Purification, crystallization and preliminary X-ray diffraction analysis of the Kelch-like motif region of mouse Keap1

Keap1 (Kelch‐like ECH‐associating protein 1) is a negative regulator of the Nrf2 transcription factor in the cytoplasm. The Kelch/DGR (double‐glycine repeat) domain of Keap1 associates with Nrf2 as well as with actin filaments. A recombinant protein containing both the Kelch/DGR domain and the C‐­terminal region of mouse Keap1 was expressed in Escherichia coli, purified to near‐homogeneity and crystallized by the sitting‐drop vapour‐diffusion method. The crystal belongs to space group P61 or P65, with unit‐cell parameters a = b = 102.95, c = 55.21 Å, and contains one molecule in the asymmetric unit. A complete diffraction data was collected to 2.25 Å resolution using an R‐AXIS IV++ imaging plate mounted on an RA‐Micro7 Cu Kα rotating‐anode X‐ray generator.