LanthaScreen™ fluorescent nuclear receptor coregulator peptides contain known interaction motifs and are labeled with fluorescein. These peptides are matched and validated to complement the LanthaScreen™ TR-FRET Nuclear Receptor Coregulator Assays. Assays developed using these reagents enable primary or secondary screening of nuclear receptor agonists and/or antagonists.

How they work
Ligand binding to nuclear receptors causes conformational changes in the receptor, resulting in a cascade of events, including dissociation of repressor proteins, association of coactivator proteins, and assembly of pol II and other transcriptional factors for activation of target genes. TR-FRET based assays can be developed using the LanthaScreen™ panel of fluorescein-labeled coregulator peptides to investigate conformational changes of nuclear receptors upon ligand binding, either by determining the affinity of ligand-bound receptor for different coregulator peptides, or by identifying additional agonists or antagonists via displacement or recruitment of a specific coregulator peptide. In the LanthaScreen™ TR-FRET RXR beta Coactivator Assay, a terbium (Tb)-labeled anti-GST antibody is used to indirectly label GSTtagged RXR beta protein. An agonist (9-cis Retinoic Acid) added to the receptor which, upon ligand binding, causes a conformational change resulting in recruitment of the Fl-D22 coactivator peptide (Figure 1). The binding of the fluorescent coregulator peptide to RXR beta causes an increase in the TR-FRET emission ratio (Figure 2).

Contents and Storage:
LanthaScreen™ fluorescent nuclear receptor coregulator peptides are supplied as 100 μM solutions in peptide-appropriate buffers. Store peptides at -20°C.