Adenosine receptors (ARs) and P2Y receptors (P2YRs) constitute part of the purinergic signalosome and are targets for drug discovery in the immune system and central nervous system. They consist of 12 subtypes of G protein-coupled receptors: four subtypes of ARs (coupled to Gi- or Gs-protein-mediated changes in cAMP levels) and eight subtypes of P2YRs (coupled to Gq- or Gi-proteins). Recently, high affinity and selective fluorescent agonists and antagonists have been reported as ligand probes of adenosine and P2Y receptors. These compounds provide new assay opportunities for characterizing binding at the receptor orthosteric and allosteric sites, the allosteric interactions between pairs of protomeric proteins in dimeric receptors (either hetero- or homodimers), kinetics of receptor binding and other pharmacological parameters. They have provided readily accessible assay options, in cases where high affinity radioligands are not available. Fluorescent ligands have found application both in cell membrane preparations, for example using fluorescence polarization, and in whole cells using flow cytometry (FCM), confocal microscopy and fluorescence correlation spectroscopy (FCS). Fluorescent purine receptor ligands are used in bioluminescence resonance energy transfer (BRET) studies in combination with a fluorescently-labeled receptor protein. Moreover, fluorescent agonists can be informative about agonist-induced internalization of GPCRs. Molecular modeling based on receptor structures and homology models often identifies a bitopic binding mode, in which the pharmacophore binds at a known orthosteric binding site and the fluorophore may interact with the extracellular loop (EL) regions of the receptor to enhance affinity. Thus, fluorescent ligands are important components of the chemical toolbox for studying GPCRs in general, and purinergic signaling, in particular.

Fluorescent agonists and antagonists for probing purinergic adenosine and P2Y receptors

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.