Abstract
G protein-coupled receptors (GPCRs) make up the largest and most diverse family of transmembrane proteins and respond to a wide variety of stimuli including biogenic amines, peptides, bioactive lipids, hormones, and light (1,2). Agonist binding to these receptors activates intracellular signalling events mediated by G proteins, such as modulation of intracellular cyclic adenosine monophosphate (cAMP) levels or Ca2+ mobilization. To date, there are approx 250 characterized nonsensory GPCRs and a further 140 genes predicted to be GPCRs for which the endogenous or natural ligand is unknown—the “orphan” GPCRs (oGPCRs) (3–5). Historically, GPCRs, especially those in the aminergic receptor subfamily, have proved amenable to the design of synthetic agonists and antagonists of their activity. Of the top-selling prescription drugs in 2002, more than 33% act through GPCRs and provide greater than $25 billion in worldwide pharmaceutical sales. Therefore, considerable effort has been made to identify cognate ligands for oGPCRs and functionally characterize these receptors in order to elucidate their physiological and therapeutic relevance.
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Marinissen, M.J., and Gutkind, J.S. (2001) G protein-coupled receptors and signalling networks: emerging paradigms. Trends Pharmacol. Sci. 22(7), 368–376.
Baldwin, J.M. (1994) Structure and function of receptors coupled to G proteins. Curr. Opin. Cell. Biol. 6(2), 180–190.
Marchese, A., George, S.R., Kolakowski, L.F., Lynch, K.R., and O'Dowd, B.F. (1999) Novel GPCRs and their endogenous ligands: expanding the boundaries of physiology and pharmacology. Trends Pharmacol. Sci. 20(9), 370–375.
Wilson, S., Bergsma, D.J., Chambers, J.K., et al. (1998) Orphan G protein-coupled receptors: the next generation of drug targets? Br. J. Pharmacol. 125(7), 1387–1392.
Howard, A.D., McAllister, G., Feighner, S.D., et al. (2001) Orphan G protein-coupled receptors and natural ligand discovery. Trends Pharmacol. Sci. 22(3), 132–140.
Pangalos, M.N. and Davies, C. H. (2002) Understanding G Protein-Coupled Receptors and Their Role in CNS. Oxford University Press, Oxford, UK: 63–86.
Robas, N., Mead, E. and Fidock, M. (2003) MrgX2 is a high potency cortistatin receptor expressed in dorsal root ganglion. J. Biol. Chem. 278(45), 44,400–44,404.
Uhlenbrock, K., Gassenhuber, H., and Kostenis, E. (2002) Sphingosine 1-phosphate is a ligand of the human gpr3, gpr6 and gpr12 family of constitutively active G protein-coupled receptors. Cell Signal 14(11), 941–953.
Lembo, P.M., Grazzini, E., Groblewski, T., et al. (2002): Proenkephalin A gene products activate anew family of sensory neuron-specific GPCRs. Nat. Neurosci. 5(3): 201–209.
Ohtaki, T., Shintani, Y., Honda, S., et al. (2001) Metastasis suppressor gene KiSS-1 encodes peptide ligand of a G protein-coupled receptor. Nature 411(6837), 613–617.
Hill, J., Duckworth, M., Murdock, P., et al. (2001) Molecular cloning and functional characterization of MCH2, a novel human MCH receptor. J Biol Chem, 276(23), 20,125–20,129.
Offermanns, S. and Simon, M. (1995) Gα15 and Gα16 Couple a Wide Variety of Receptors to Phospholipase C. J. Biol. Chem., 270(25), 15,175–15,180.
Milligan, G. and Rees, S. (1999) Chimeric Gα proteins: their potential use in drug discovery. Trends Pharmacol. Sci., 20, 118–124.
Kostenis, E. (2001) Is Gα16 the optimal tool for fishing ligands of orphan G protein-coupled receptors? Trends Pharmacol. Sci., 22, 560–564.
Minta, A., Kao, J.P., and Tsien, R.Y. (1989). Fluorescent indicators for cytosolic calcium based on rhodamine and fluorescein chromophores. J. Biol. Chem. 264(14), 8171–8178.
Di Virgilio, F., Steinberg, T.H., Silverstein, S.C. (1989) Organic-anion transport inhibitors to facilitate measurement of cytosolic free Ca2+ with fura-2. Methods Cell Biol. 31, 453–462.
Shimomura, Y., Harada, M., Goto, M., et al. (2002) Identification of neuropeptide W as the endogenous ligand for orphan G protein-coupled receptors GPR7 and GPR8. J. Biol. Chem. 277, 35,826–35,832.
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Robas, N.M., Fidock, M.D. (2005). Identification of Orphan G Protein-Coupled Receptor Ligands Using FLIPR® Assays. In: Davenport, A.P. (eds) Receptor Binding Techniques. Methods in Molecular Biology™, vol 306. Humana Press. https://doi.org/10.1385/1-59259-927-3:017
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DOI: https://doi.org/10.1385/1-59259-927-3:017
Publisher Name: Humana Press
Print ISBN: 978-1-58829-420-3
Online ISBN: 978-1-59259-927-1
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