Development of Clickable Photoaffinity Ligands for Metabotropic Glutamate Receptor 2 Based on Two Positive Allosteric Modulator Chemotypes

Shane D. Hellyer, Shaili Aggarwal, Amy N.Y. Chen, Katie Leach, David J. Lapinsky, Karen J. Gregory

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3 Citations (Scopus)


The metabotropic glutamate receptor 2 (mGlu2) is a transmembrane-spanning class C G protein-coupled receptor that is an attractive therapeutic target for multiple psychiatric and neurological disorders. A key challenge has been deciphering the contribution of mGlu2 relative to other closely related mGlu receptors in mediating different physiological responses, which could be achieved through the utilization of subtype selective pharmacological tools. In this respect, allosteric modulators that recognize ligand-binding sites distinct from the endogenous neurotransmitter glutamate offer the promise of higher receptor-subtype selectivity. We hypothesized that mGlu2-selective positive allosteric modulators could be derivatized to generate bifunctional pharmacological tools. Here we developed clickable photoaffinity probes for mGlu2 based on two different positive allosteric modulator scaffolds that retained similar pharmacological activity to parent compounds. We demonstrate successful probe-dependent incorporation of a commercially available clickable fluorophore using bioorthogonal conjugation. Importantly, we also show the limitations of using these probes to assess in situ fluorescence of mGlu2 in intact cells where significant nonspecific membrane binding is evident.

Original languageEnglish
Pages (from-to)1597-1609
Number of pages13
JournalACS Chemical Neuroscience
Issue number11
Publication statusPublished - 3 Jun 2020


  • allosteric modulator
  • chemical probe
  • click chemistry
  • metabotropic glutamate receptor
  • Photoaffinity labeling
  • schizophrenia

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