Analytical Neuropharmacology

Dr Celine Valant
Monash Research Fellow
Laboratory Director

Professor Arthur Christopoulos
Dean, Faculty of Pharmacy & Pharmaceutical Sciences
Laboratory Deputy Director

Project areas | Key publications | Lab members | Collaborations | Funding

Project areas

Research focus

G protein-coupled receptors (GPCRs) represent the largest family of receptor proteins encoded by the human genome and the biggest class of current drug targets. These proteins can concomitantly interact with diverse endogenous and exogenous ligands and adopt multiple conformational states that couple to diverse signalling pathways. Our laboratory focuses on two key paradigms of drug action that arise as a consequence of these properties of GPCRs, specifically, allosteric modulation and biased agonism. These paradigms are revolutionizing modern drug discovery, and we investigate them using a multidisciplinary approach that encompasses structural and computational biology, molecular and mathematical modelling, medicinal chemistry, biochemistry and cellular signal transduction, native tissue bioassays and preclinical animal models. We are particularly interested in understanding how the phenomena of allosteric modulation and biased agonism can be applied to GPCRs implicated in neuropsychiatric disorders, such as schizophrenia, and neurodegenerative disorders, such as Alzheimer’s disease, but we also investigate GPCR targets implicated in other disease states.  We apply a multi-disciplinary approach to interrogating GPCRs with a view to developing novel chemical probes and potential therapeutic leads.

Our laboratory applies multidisciplinary approaches to study novel paradigms of drug action at GPCRs.

Analytical Pharmacology

A key focus of our laboratory is on the interpretation of drug actions in terms of underlying hypothetical mechanisms. This involves the combination of appropriately designed bioassays, either at the cellular or whole tissue level, with mathematical models that can shed light on the molecular properties of drugs in a manner that allows novel predictions to be made about the compounds or target(s) under investigation. An application of quantitative models of drug action is particularly relevant to understanding allosteric modulation and biased agonism at GPCRs, and we are constantly aiming to develop new approaches that can lead to more informative experimental design and therapeutic agents with improved biological properties.

GPCRs possess multiple topographically distinct binding sites and isomerize between multiple states, giving rise to distinct pharmacological patterns of allosterism and biased agonism. These can be quantified by determination of key parameters (left) and used to construct "Webs of Bias", an example of which is shown on the right for signalling of three different ligands at the adenosine A1 receptor. This allows for quantitative compound "fingerprinting".

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Structural and Computational Biology

We are very interested in understanding the molecular, and even atomistic, basis of how drugs can interact with GPCRs to modulate their biology, and how this information can be exploited to facilitate structure-based drug design. To address this, we utilize mutagenesis, biophysical techniques, x-ray crystallography, cryo-electron microscopy (cryo-EM) and cutting-edge computational modelling and docking methods to understand receptor dynamics and drug-receptor interactions, especially in the context of allosteric modulators and biased agonists.

Understanding the structural basis of GPCR allosteric modulation. Left: high resolution crystal structure of the M2 muscarinic acetylcholine receptor bound to an activating nanobody (Nb9-8, green), orthosteric agonist (iperoxo, yellow) and positive allosteric modulator (LY2119620, purple). Right: movie showing molecular dynamics simulation of a negative allosteric modulator drug binding to the M2 muscarinic acetylcholine receptor.

Chemical and Cellular Biology

We have numerous projects that sit at the interface of chemistry and biology, using small-molecules to interrogate GPCRs and their associated signalling pathways. These studies focus on the generation of novel chemical probes as tools to illuminate biological processes, as well as the discovery of potential therapeutic leads that can progress in drug discovery programs. Our main focus in this regard is in the optimization of structure-activity relationships underlying allosteric modulators and biased agonist activity. To achieve this, we combine analytical pharmacology with medicinal chemistry, resonance energy transfer techniques and multi-tiered signal transduction assays that encompass a broad range of cellular activities, including assays of intracellular second messengers, protein-protein interactions, trafficking, reporter genes, whole cell metabolism and morphological changes. These are performed in both recombinant and native cells, with a view to predicting optimal behaviours for perturbing whole organ systems in a therapeutic setting.

Association and dissociation of an allosteric ligand from/to its binding site.
We use Fluorescence Resonance Energy Transfer (FRET) to quantify ligand-receptor interactions

Left: Delineating the structure-activity relationships of allosteric modulators of the M1 muscarinic acetylcholine receptor. Right: A rationally designed 'bitopic' ligand of the adenosine A1 receptor, comprised  of the orthosteric agonist, adenosine, linked to a positive allosteric modulator. This hybrid molecule is a biased agonist.

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Animal Models of Physiology and Disease

We strive to translate our knowledge of GPCR structure, function and signalling into a deep understanding of the mechanisms of physiological regulation and disease. A main thrust of our laboratory in this regard is to understand how allosteric modulators and biased agonists can be used to treat neurological, metabolic and other diseases. We utilize a suite of animal models of behaviour or metabolic dysfunction, including studies in transgenic mice where key proteins have been removed or modified to understand the physiological and pathophysiological relevance of allosteric modulation and biased agonism. We are particularly interested in the potential for untapped endogenous allosteric and biased ligands in both health and disease.

Translational potential of allosteric modulation. Preclinical workflow illustrating our studies of the M4 muscarinic receptor allosteric modulator, LY2033298, as assessed by cell-based signalling studies, receptor mutagenesis, native brain studies (neurotransmitter release in slices and microdialysis), and models of behaviour in wild type and knockout mice.

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Key publications

Research papers

Draper-Joyce, C.J., Khosouei, M., Thal. D.M., Liang, Y.L., Nguyen, A.T.N., Gurness, S.G.B., Venugopal, H., Baltos, J., Plitzko, J.P., Danev, R., Baumeisterm W., May, L.T., Wootten, D., Sexton, P.M., Glukhova, A. and A. Christopoulos (2018) Structure of the adenosine-bound human A1 receptor-Gi complex. Nature 558: 559-563.

Liang, Y.L., Khoshouei, M., Deganuti, G., Glukhova, A., Koole, C., Peat, T.S., Radjainia, M., Plitzko, J.M., Baumeister, W., Miller, L.M., Hay, D.L., Christopoulos, A., Reynolds, C.A., Wootten, D. and P M. Sexton (2018) Cryo-EM structure of the active, Gs-protein complexed, human CGRP receptor. Nature 561: 492-497.

Berizzi, A., Perry, C., Shackleford, D., Lindsley, C., Jones, C., Chen, N., Sexton, P.M., Christopoulos, A.*, Langmead, C.J. and A.J. Lawrence (2018) Muscarinic M5 receptors modulate ethanol seeking in rats. Neuropsychopharmacol., 43: 1510-1517. *Co-corresponding.

Korczynska, M., Clark, M.J., Valant, C.†, Moo, E.V., Abold, S., Weiss, D.R., Torosyan, H., Huang, W., Kruse, A.C., May, L.T., Baltos, J., Sexton, P.M., Kobilka, B.K., Christopoulos, A.*, Shoichet, B.K., and R.K. Sunahara (2018) Structure-based discovery of selective positive allosteric modulators of antagonists for the M2 muscarinic acetylcholine receptor. Proc. Nat. Acad. Sci. (USA) 115: E2419-E2428. †Co-first; *Co-corresponding.

Liang, Y.-L., Khosouei, M., Glukhova, A., Furness, S.G.B., Clydesdale, L., Koole, C., Troung, T.T., Thal, D.M., Lei, S., Radjainia, M., Danev, R., Baumeister, W., Wang, M.-W., Christopoulos, A., Sexton, P.M. and D. Wootten (2018) Phase-plate cryo-EM structure of a biased agonist-bound human GLP-1 receptor-Gs complex. Nature 555: 121-125.

Liang, Y.L., Khoshouei, M., Radjainia, M., Zhang, Y., Glukhova, A., Tarrasch, J., Thal, D.M., Furness, S.G.B., Christopoulos, G., Coudrat, T., Danev, R., Baumeister, W., Miller, LJ., Christopoulos, A., Kobilka, B.K., Wootten, D., Skiniotis, G. and P.M. Sexton (2017) Phase-plate cryo-EM structure of a class B GPCR-G protein complex. Nature 546: 118-123.

Glukhova, A., Thal, D.T., Nguyen, A.T.N., Vecchio, E.A., Jörg, M., Scammells, P.J., May, L.T., Sexton, P.M. and A. Christopoulos (2017) Structure of the adenosine A1 receptor reveals the basis for subtype selectivity. Cell 168: 867-877.

Bradley, S.J., Bourgognon, J.-M.,Sanger, H.E., Verity, N.,Mogg, A., White, D.J., Butcher, A.J., Moreno,J.A.,Molloy,C.,Macedo-Hatch, T., Edwards, J.E., Wess, J., Pawlak, R., Read, D.J., Sexton, P.M., Broad, L.M., Steinert, J.R., Mallucci, G.R., Christopoulos, A., Felder, C.C. and A.B. Tobin (2017) M1-muscarinic allosteric modulators slow prion neurodegeneration and restore memory loss. J. Clin. Invest. 127: 487-499.

Qin, R.C.X., May, L.T., Li, R., Cao, N., Rosli, S., Deo, M., Alexander, A.E., Horlock, D., Bourke, J.E., Yang, Y.H., Stewart, A.G., Kaye, D.M., Du, X.-J., Sexton, P.M., Christopoulos, A., Gao X.-M. and R. H. Ritchie (2017) Small-molecule biased formyl peptide receptor agonist Compound-17b protects against myocardial ischemia-reperfusion injury in mice. Nature Comm. 8: 14232.

Furness, S.G.B., Liang, Y.-L., Nowell, C.J., Halls, M.L., Wookey, P.J., Dal Maso, E., Inoue, A., Christopoulos, A., Wootten, D. and P.M. Sexton (2016) Ligand-dependent modulation of G protein conformation alters drug efficacy. Cell. 167: 739-749.

Miao, Y., Goldfeld, D., Moo, E.V., Sexton, P.M., Christopoulos, A., McCammon, A.J. and C. Valant (2016) Accelerated structure-based design of chemically diverse allosteric modulators of a muscarinic G protein-coupled receptor. Proc. Nat. Acad. Sci. (USA). 113: E5675-E5684.

Wootten, D., Reynolds, C.A., Smith, K.J., Mobarec, J.C., Koole, C., Savage, E., Pabreja, K., Simms, J., Sridhar, R., Furness, S.G.B., Liu, M., Thompson, P.E., Miller, L.J., Christopoulos, A. and P.M. Sexton (2016) The GLP-1 receptor extracellular surface is a molecular trigger for biased agonism. Cell. 165: 1632-1643.

Leach, K., Gregory, K.J., Kufareva, I., Khajehali, E., Cook, A.E., Abagyan, R., Conigrave, A.D., Sexton P.M. and A. Christopoulos (2016) Towards a structural understanding of allosteric drugs at the human calcium sensing receptor Cell Res. 26: 574-592.

Klein Herenbrink, C., Sykes, D.A., Donthamsetti, P., Canals, M., Coudrat, T., Shonberg, J., Scammells, P.J., Capuano, B., Sexton, P.M., Charlton, S.J., Javitch, J.A., Christopoulos, A.* and J.R. Lane (2016) The role of kinetic context in apparent biased agonism at GPCRs.  Nature Comm. 7: 10842 *Co-corresponding.

Thal, D.M., Sun, B., Feng, D., Nawaratne, V., Leach, K., Felder, C.C., Bures, M.G., Evans, D.A., Weis, W.I., Bachhawat, P., Kobilka, T.S., Sexton, P.M., Kobilka, B.M. and A. Christopoulos (2015) Crystal structures of the M1 and M4 muscarinic acetylcholine receptors and insights into their allosteric modulation. Nature. 531: 335–340.

Lane, J.R., Donthamsetti, P., Shonberg, J., Draper-Joyce, C.J., Dentry, S., Michino, M., Shi, L., López, L., Scammells, P.J., Capuano, B., Sexton, P.M., Javitch, J.A. and A. Christopoulos (2014) A new mechanism of allostery in a G protein-coupled receptor dimer. Nature Chem. Biol. 10: 745-752.

Valant, C., May, L.T., Aurelio, L., Chuo, C.H., White, P.J., Baltos, J., Sexton, P.M., Scammells, P.J. and A. Christopoulos (2014) Separation of on-target efficacy from adverse effects through rational design of a bitopic adenosine receptor agonist. Proc. Nat. Acad. Sci. (USA)111: 4614-4619.

Dror, R.O., Green, H.F., Valant, C.†, Borhani, D.W., Valcourt, J.R., Pan, A.C., Arlow, D.H., Canals, M., Lane, J.R., Rahmani, R., Baell, J.B., Sexton, P.M., Christopoulos, A*. and D.E. Shaw (2013) Structural basis for modulation of a G-protein-coupled receptor by allosteric drugs. Nature. 503: 295-299.†Co-first; *Co-corresponding.

Kruse, A.C., Ring, A.M., Manglik, A., Hu, J., Hu, K., Eitel, K., Hübner, H., Pardon, E., Valant, C., Sexton, P.M., Christopoulos, A., Felder, C.C., Gmeiner, P., Steyert, J., Weiss, W.I., Garcia, K.C., Wess, J. and B.K. Kobilka (2013) Activation and allosteric modulation of a muscarinic acetylcholine receptor. Nature. 504: 101-106.

Mistry, S., Valant, C., Sexton, P., Capuano, B., Christopoulos, A.* and P.J. Scammells (2013) Synthesis and pharmacological profiling of analogues of BQCA as allosteric modulators of the M1 muscarinic receptor. J. Med. Chem. 56: 5151-5172. *Co-corresponding.

Leach, K., Wen, A., Cook, A.E., Sexton, P.M., Conigrave, A.D, and A. Christopoulos (2013) Impact of clinically relevant mutations on the pharmacoregulation and signaling bias of the calcium sensing receptor by positive and negative allosteric modulators. Endocrinology154: 1105-1116.

Gregory, K.J., Sexton, P.M., Tobin, A.B. and A. Christopoulos (2012) Stimulus bias provides evidence for conformational constraints in the structure of a G protein-coupled receptor. J. Biol. Chem. 287: 37066-37077.

Kenakin, T., Watson, C., Muniz-Medina, V. and A. Christopoulos (with Appendix by S. Watson) (2012) A simple method to quantify functional selectivity and agonist bias. ACS Chem. Neurosci. 3: 193-203.

Wootten D., Savage E.E., Valant C., May L.T., Sloop K.W., Ficorilli J., Showalter A.D., Willard F.S., Christopoulos A. and P.M. Sexton. Allosteric modulation of endogenous metabolites as an avenue for drug discovery.Mol Pharmacol., 2012, 82(2):281-90.

Valant, C., Felder, C.C., Sexton, P.M. and A. Christopoulos (2012) Probe-dependence in the allosteric modulation of a G protein-coupled receptor:  Implications for detection and validation of allosteric ligand effects.  Mol. Pharmacol. 81: 41-52.

Canals, M., Lane, J.R., Wen, A., Scammells, P.J., Sexton, P.M. and A. Christopoulos (2012) A Monod-Wyman-Changeux mechanism can explain G protein-coupled receptor (GPCR) allosteric modulation. J. Biol. Chem. 287: 650-659.

Valant, C., Gregory, K.J., Hall, N.E., Scammells, P.J., Lew, M.J., Sexton, P.M. and A. Christopoulos (2008) A novel mechanism of G protein-coupled receptor functional selectivity: muscarinic partial agonist McN-A-343 as a bitopic orthosteric/allosteric ligand, J. Biol. Chem, 283: 29312-29321.


Wootten, D., Christopoulos, A., Solano, M.M., Babu, M.M., and P.M. Sexton (2018) Mechanisms of signalling and bias in G-protein coupled receptors. Nature Rev. Mol. Cell Biol. 19: 638-653.

Thal, D.M., Glukhova, A., Sexton P.M. and A. Christopoulos (2018) Structural insights into G-protein-coupled receptor allostery. Nature 559: 45-53.

Lane, J.R., May, L.T., Parton, R.G., Sexton, P.M and A. Christopoulos (2017) A kinetic view of GPCR allostery and biased agonism. Nature Chem. Biol. 13: 929-937.

Wootten, D., Miller, L.J., Koole, C, Christopoulos, A. and P.M. Sexton (2017) Allostery and biased agonism at class B G protein-coupled receptors. Chem. Rev. 117: 111-138.

Changeux, J.P. and A. Christopoulos (2016) Allosteric modulation as a unifying mechanism for receptor function and regulation. Cell. 166: 1084-1102.

van der Westhuizen E.T., Valant C., Sexton P.M. and A. Christopoulos. Endogenous allosteric modulators of G protein-coupled receptors. J. Pharm. Exp. Ther. 2015, 353: 246–260.

Gentry, P.R., Sexton, P.M. and A. Christopoulos (2015) Novel allosteric modulators of G protein-coupled receptors. J. Biol. Chem. 290: 19478-19488.

Christopoulos, A. (2014) Advances in GPCR allostery: From function to structure.  Mol. Pharmacol. 86: 463-478.

Christopoulos, A., Changeux, J.P., Catterall, W.A., Fabbro, D., Burris, T.P., Cidlowski, J.A., Olsen, R.W., Peters, J.A., Neubig, R.R., Pin, J.P., Sexton, P.M., Kenakin, T.P., Ehlert, F.J., Spedding M. and C.J. Langmead (2014) International Union of Basic and Clinical Pharmacology. XC. Multi-site Pharmacology: Recommendations for the nomenclature of receptor allosterism and allosteric ligands. Pharmacol. Rev. 66: 918-947.

Kruse, A.C., Kobilka, B.K., Gautam,D.,Sexton, P.M., Christopoulos, A. and J., Wess (2014) Insights into muscarinic acetylcholine receptor biology, pharmacology, and structure. Nature Rev. Drug Discovery, 13: 549-560.

Kenakin, T. and A. Christopoulos (2013) Signaling bias in new drug discovery: Detection, quantification and therapeutic impact. Nature Rev. Drug Discovery 12: 205–216.

Valant, C., Lane, J.R., Sexton, P.M. and A. Christopoulos (2012) The best of both worlds? Bitopic orthosteric/allosteric ligands of G protein-coupled receptors. Ann. Rev. Pharmacol. Toxicol., 52: 153-178.

Wootten, D., Christopoulos, A. and P.M. Sexton (2013) Emerging paradigms in GPCR allostery: Implications for drug discovery. Nature Rev. Drug Discovery 12: 630-644.

Keov, P., Sexton, P.M. and A. Christopoulos (2011) Allosteric modulation of G protein-coupled receptors: A pharmacological perspective. Neuropharmacol. 60: 24-35.

Kenakin, T. and A. Christopoulos (2011) Analytical pharmacology: The impact of numbers on pharmacology. Trends Pharmacol. Sci. 32: 189-196.

Conn, P.J., Christopoulos, A. and C.W. Lindsley (2009) Allosteric modulators of GPCRs: A novel approach for the treatment of CNS disorders. Nature Rev. Drug Discovery 8: 41-54.

Leach, K., Sexton, P.M. and A. Christopoulos (2007) Allosteric modulators of GPCRs: Taking advantage of permissive receptor pharmacology. Trends Pharmacol. Sci. 28: 382-389.

May, L.T., Leach, K., Sexton, P.M. and A. Christopoulos (2007) Allosteric modulation of G protein-coupled receptors, Ann. Rev. Pharmacol. Toxicol., 47: 1-51.

Christopoulos, A. and T. Kenakin (2002) G protein-coupled receptor allosterism and complexing, Pharmacol. Rev. 54: 323-374.

Christopoulos, A. (2002) Allosteric binding sites on cell-surface receptors: Novel targets for drug discovery. Nature Rev. Drug Discovery 1: 198-210.

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Lab members

  • Dr Joanne Baltos
  • Dr Chris Choy
  • Dr Chris Draper-Joyce
  • Dr Elham Khajehali
  • Dr Simon McKenzie-Nickson
  • Dr Vi Pham
  • Dr Georgina Thompson
  • Mr Geoff Thompson
  • Dr Ziva Vuckovic Mueller
  • Dr Emma van der Westhuizen
  • Wessel Burger, PhD Candidate
  • Huong Nguyen, PhD Candidate
  • Jinn Chong, Honours Student
  • Luke Williams, Honours Student


Analytical Pharmacology: Understanding Allostery and Biased Agonism

Structural and Computational Studies of GPCRs

  • Professor Patrick Sexton, Drug Discovery Biology, MIPS
  • Dr David Thal, Drug Discovery Biology, MIPS
  • Dr Alisa Glukhova, Drug Discovery Biology, MIPS
  • Dr Katie Leach, Drug Discovery Biology, MIPS
  • Dr Karen Gregory, Drug Discovery Biology, MIPS
  • A/Prof Denise Wootten, Drug Discovery Biology, MIPS
  • Dr Chris Langmead, Drug Discovery Biology, MIPS
  • Dr Daniel Scott, Howard Florey Institute, Melbourne
  • A/Prof Ron Dror, Stanford University, USA
  • Professor Larry Miller, Mayo Clinic, USA
  • Dr Yinlong Miao, University of California, San Diego, USA
  • Professor Brian Shoichet, University of California, San Francisco, USA
  • Professor Jens Carlsson, Uppsala University, Sweden

GPCR Drug Discovery

Allosteric modulation for treatment of neuropsychiatric disease

  • Professor Patrick Sexton, Drug Discovery Biology, MIPS
  • Professor Peter Scammells, Medicinal Chemistry, MIPS
  • Dr Chris Langmead, Drug Discovery Biology, MIPS
  • Professor Mark Febbraio, Drug Discovery Biology, MIPS
  • Dr Ben Capuano, Medicinal Chemistry, MIPS
  • Professor Susan Charman, Centre for Drug Candidate Optimisation, MIPS
  • Dr David Shackleford, Centre for Drug Candidate Optimisation, MIPS
  • Professor Christos Pantelis, University of Melbourne
  • Professor Rob Parton, University of Queensland
  • Professor Stan Skafidas, University of Melbourne
  • Professor Andrew Tobin, University of Glasgow, UK
  • Professor Andrew Lawrence, Florey Institute of Neuroscience and Mental Health
  • Dr Jess Nithianantharajah, Florey Institute of Neuroscience and Mental Health

Novel modes of targeting adenosine receptors in ischemia-reperfusion and neurological diseases

Allosteric and biased modulation of the calcium sensing receptor in endocrinological disease

Allostery and bias at the glucagon-like peptide 1 receptor and their impact on metabolic disease

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2019 – 2023: “Translating membrane proteins into therapeutics: from bedside to bench”, National Health and Medical Research Council of Australia Program Grant.
2019 – 2021: “Discovering novel allosteric probes of muscarinic acetylcholine receptors”, Australian Research Council Discovery Grant.
2019 – 2021: “Chemical-biology approaches to pathway selective adenosine receptor ligands”, Australian Research Council Discovery Grant.
2018 – 2022: “Adenosine A1 receptor modulation: Structure, dynamics & novel pharmacological interventions”, National Health and Medical Research Council of Australia Project Grant.
2016 – 2020: Wellcome Trust Collaborative Award, “Collaborative network to define the molecular determinants of G protein-coupled receptor clinical efficacy”.
2016 – 2020: National Health and Medical Research Council of Australia Senior Principal Research Fellowship ID No APP1102950.
2017– 2025: “GPCR Drug Discovery”, contract with Servier Laboratories.

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