An allosteric role for receptor activity-modifying proteins in defining GPCR pharmacology


G protein-coupled receptors are allosteric proteins that control transmission of external signals to regulate cellular response. Although agonist binding promotes canonical G protein signalling transmitted through conformational changes, G protein-coupled receptors also interact with other proteins. These include other G protein-coupled receptors, other receptors and channels, regulatory proteins and receptor-modifying proteins, notably receptor activity-modifying proteins (RAMPs). RAMPs have at least 11 G protein-coupled receptor partners, including many class B G protein-coupled receptors. Prototypic is the calcitonin receptor, with altered ligand specificity when co-expressed with RAMPs. To gain molecular insight into the consequences of this protein–protein interaction, we combined molecular modelling with mutagenesis of the calcitonin receptor extracellular domain, assessed in ligand binding and functional assays. Although some calcitonin receptor residues are universally important for peptide interactions (calcitonin, amylin and calcitonin gene-related peptide) in calcitonin receptor alone or with receptor activity-modifying protein, others have RAMP-dependent effects, whereby mutations decreased amylin/calcitonin gene-related peptide potency substantially only when RAMP was present. Remarkably, the key residues were completely conserved between calcitonin receptor and AMY receptors, and between subtypes of AMY receptor that have different ligand preferences. Mutations at the interface between calcitonin receptor and RAMP affected ligand pharmacology in a RAMP-dependent manner, suggesting that RAMP may allosterically influence the calcitonin receptor conformation. Supporting this, molecular dynamics simulations suggested that the calcitonin receptor extracellular N-terminal domain is more flexible in the presence of receptor activity-modifying protein 1. Thus, RAMPs may act in an allosteric manner to generate a spectrum of unique calcitonin receptor conformational states, explaining the pharmacological preferences of calcitonin receptor-RAMP complexes. This provides novel insight into our understanding of G protein-coupled receptor-protein interaction that is likely broadly applicable for this receptor class.

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Divisions: College of Health & Life Sciences > School of Biosciences
College of Health & Life Sciences > Aston Pharmacy School
College of Health & Life Sciences > Chronic and Communicable Conditions
College of Health & Life Sciences
College of Health & Life Sciences > School of Biosciences > Cellular and Molecular Biomedicine
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Publication ISSN: 2056-5968
Last Modified: 20 May 2024 07:15
Date Deposited: 26 Sep 2016 10:40
Full Text Link: http://www.natu ... /celldisc201612
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PURE Output Type: Article
Published Date: 2016-05-17
Accepted Date: 2016-02-24
Submitted Date: 2016-01-12
Authors: Gingell, Joseph J.
Simms, John (ORCID Profile 0000-0002-4675-0902)
Barwell, James
Poyner, David R. (ORCID Profile 0000-0003-1590-112X)
Watkins, Harriet A.
Pioszak, Augen A.
Sexton, Patrick M.
Hay, Debbie L.



Version: Published Version

License: Creative Commons Attribution

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