The TR-FRET PPAR (peroxisome proliferator activated receptor) alpha Coactivator Assay provides a sensitive and robust method for high-throughput screening of potential PPAR alpha ligands as agonists or antagonists of ligand-dependent coactivator recruitment. The kit uses a terbium (Tb)-labeled anti-GST antibody, a fluorescein-labeled coactivator peptide, and a human recombinant PPAR alpha ligand-binding domain (PPAR alpha-LBD) that is tagged with glutathione-S-transferase (GST) in a homogeneous mix-and-read assay format.
Agonist mode:
When running the TR-FRET PPAR alpha Coactivator Assay in agonist mode (to identify agonist compounds), PPAR alpha- LBD is added to ligand test compounds followed by addition of a mixture of the fluorescein-coactivator peptide and Tb-labeled anti-GST antibody. After an incubation period at room temperature, the 520 nm/495 nm TR-FRET ratio is calculated and can be used to determine the EC50 from a dose response curve of the compound. Based on the biology of the PPAR alpha-coactivator peptide interaction, this ligand EC50 is a composite value representing the amount of ligand required to bind to receptor, effect a conformational change, and recruit coactivator peptide.
Antagonist mode:
When the TR-FRET PPAR alpha Coactivator Assay is run in antagonist mode (to identify antagonist compounds), PPAR alpha-LBD is added to ligand test compounds followed by addition of a mixture of agonist, fluorescein-coactivator peptide, and Tb-labeled anti-GST antibody. The concentration of agonist used in this mode is the EC80 concentration as determined by first running the assay in agonist mode.