Convenient Retinoid X Receptor Binding Assay Based on Fluorescence Change of the Antagonist NEt-C343

Kayo Yukawa-Takamatsu, Yifei Wang, Masaki Watanabe, Yuta Takamura, Michiko Fujihara, Mariko Nakamura-Nakayama, Shoya Yamada, Shota Kikuzawa, Makoto Makishima, Mayu Kawasaki, Sohei Ito, Shogo Nakano, Hiroki Kakuta

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Retinoid X receptor (RXR) modulators (rexinoids) are considered to have therapeutic potential for multiple diseases, such as Alzheimer's disease and Parkinson's disease. To overcome various disadvantages of prior screening methods, we previously developed an RXR binding assay using a fluorescent RXR ligand, CU-6PMN (4). However, this ligand binds not only at the ligand-binding domain (LBD) but also at the dimer-dimer interface of hRXRα. Here, we present a new fluorescent RXR antagonist 6-[N-ethyl-N-(5-isobutoxy-4-isopropyl-2-(11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-10-carboxamido)phenyl)amino]nicotinic acid (NEt-C343, 7), which emits strong fluorescence only when bound to the RXR-LBD. It allows us to perform a rapid, simple, and nonhazardous binding assay that does not require bound/free separation and uses a standard plate reader. The obtained Ki values of known compounds were correlated with the Ki values obtained using the standard [3H]9cis-retinoic acid assay. This assay should be useful for drug discovery as well as for research on endocrine disruptors, functional foods, and natural products.

Original languageEnglish
Pages (from-to)861-870
Number of pages10
JournalJournal of medicinal chemistry
Issue number1
Publication statusPublished - Jan 14 2021

ASJC Scopus subject areas

  • Molecular Medicine
  • Drug Discovery


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