In Vitro Pharmacology >> GPCRs >> Allosteric

GPCR Profiling for Allosteric Modulators

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AllostericProfiler™ and AllostericScreener™ Services


Historically, GPCR drug development has been focused on compounds that interact with the receptors' orthosteric site; however, the orthosteric binding site can be highly conserved, making it extremely difficult to generate receptor-specific compounds.

Researchers circumnavigate this restraint by exploiting the receptor's allosteric sites. Allosteric compounds are gaining relevance because they can modulate receptor activity, allowing greater physiological control of receptor activation, and are predicted to be more selective and have a reduced potential for overdose.

Our AllostericProfiler™ receptor profiling services use a functional readout to detect allosteric compound activity.AllostericProfiler™ is the first fully validated selectivity profiling service capable of detecting a range of compound activities for over 165 GPCRs by using a unique two-addition methodology to detect of a wide variety of activities including agonist, positive allosteric modulator (PAM) and negative allosteric modulator (NAM) activity.

AllostericScreener™ screens compound libraries to identify new compounds having positive allosteric modulator (PAM) activity for a target of interest. AllostericScreener™ service employs an assay design that is similar, but slightly modified, to our standard GPCRProfiler® services. This assay design can identify both agonist and PAM activities. Therefore, you can discriminate hits that either activate the receptor directly, modulate the receptor's activity or those that have a mixture of these activities.

Advantages of our binding assay services:

  • A unique receptor screening method, allowing for detection of multiple activities including agonist, PAM, or NAM activity
  • Dual-mode screening (agonist and antagonist) in a single well means you won't miss the functionality of analogs at the directed target or off-target receptors
  • 96- or 384-plate FLIPR™ assays with fully integrated and automated compound and plate handling
  • Experience: first company to provide outsourced broad GPCR allosteric profiling assays in 2009
  • Quick turnaround times of 1-3 weeks depending on project types

Figure 1. Distinct interactions sites for allosteric compounds.

Represented are the theoretical binding sites for an orthosteric compound (A) and an allosteric compound (B). Orthosteric and allosteric compounds can simultaneously occupy distinct sites on a GPCR to modify the receptor's activity (C).


Figure 2. Sample of experimental data generated by an AllostericProfiler™ selectivity screen on a set of allosteric modulators against Class A, B and C GPCRs.

Shown are the resulting dose response curves generated during the second addition step, in which the reference agonist was added to cells that had been treated with10 μM (or 30 μM for CGP 7930 and CGP 13501) of the indicated test compounds during the first addition step. A) α2A adrenergic family receptor. 5-(N,N-hexamethylene) amiloride, a reported α2A NAM, was found to inhibit this Class A receptor as indicated by a rightward shift in epinephrine's dose response curve. B) M4 acetylcholine muscarinic family receptor. Two compounds, VU 0152099 and VU 10010, were both found to potentiate the response of this Class A receptor to its native ligand, acetylcholine, as indicated by a leftward shift in the curve. C) CRF1 corticotropin-releasing factor family receptor. This Class B receptor was inhibited by two different molecules, NBI 27914 and antalarmin, that were previously reported to be NAMs. This inhibition is demonstrated by either the rightward shift in urocortin's potency and/or decrease in its apparent efficacy, respectively. D) GABAB receptor. Both reported GABAB receptor PAMs, CGP 7930 and CGP 13501, were able to potentiate GABA's signaling as indicated by the observed increase of GABA's potency in the presence of these PAMs.