Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor-type transcription factors with three subtypes (α, δ, and γ) that regulate cell differentiation and metabolism. Co-crystals of human PPARα-ligand-binding domain (LBD)-PPARα ligand for X-ray crystallography have been difficult to obtain. Recombinant human PPARα-LBD proteins contain intrinsic fatty acids (iFAs of Escherichia coli origin) and may be unstable without ligands during crystallization. To circumvent these limitations, we have successfully applied various crystallization techniques, including co-crystallization, cross-seeding, soaking, delipidation, and coactivator peptide supplementation. For complete details on the use and execution of this protocol, please refer to Kamata et al. (2020).