G protein-coupling and ligand selectivity of the D2L and D3 dopamine receptors

Lane, J.R., Powney, B., Wise, A., Rees, S. and Milligan, G. (2008) G protein-coupling and ligand selectivity of the D2L and D3 dopamine receptors. Journal of Pharmacology and Experimental Therapeutics, 325(1), pp. 319-330. (doi: 10.1124/jpet.107.134296)

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Publisher's URL: http://dx.doi.org/10.1124/jpet.107.134296

Abstract

The human dopamine D2L receptor couples promiscuously to multiple members of the Gαi/o subfamily. Despite the high homology of the D2L and D3 receptors, the G protein-coupling specificity of the human D3 receptor is less clearly characterized. The primary aim of this study, then, was the parallel characterization of the G protein coupling specificity of the D2L and D3 receptors. By employing both receptor-G protein fusion proteins and stable cell lines in which pertussis toxin-resistant mutants of individual Gαi-family G proteins were expressed in an inducible fashion we demonstrated highly selective coupling of the D3 receptor to Gαo1. Furthermore, by using the fusion proteins to ensure identical stoichiometry of receptor to G protein for each pairing, a range of ligands displayed higher potency and, for partial agonists, higher efficacy at the D3 receptor when coupled to Go1 as compared to the D2L receptor. The second aim of this study was to investigate the molecular basis of the above differential G protein-coupling specificity. The importance of a twelve amino acid sequence from the C-terminal end of the third intracellular loop of the D2L receptor in providing promiscuity in G protein coupling was demonstrated using a chimeric D3/D2 receptor in which the equivalent region of the D3 receptor was exchanged for this sequence. This chimera displayed D3-like affinity for [3H] spiperone and potency for agonists, but gained D2-like ability to couple to each of Gαi1-3 as well as Gαo1.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Milligan, Professor Graeme
Authors: Lane, J.R., Powney, B., Wise, A., Rees, S., and Milligan, G.
Subjects:Q Science > QH Natural history > QH345 Biochemistry
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Journal of Pharmacology and Experimental Therapeutics
ISSN:0022-3565

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