scholarly journals Molecular basis for high affinity agonist binding in GPCRs

2018 ◽  
Author(s):  
Tony Warne ◽  
Patricia C. Edwards ◽  
Andrew S. Doré ◽  
Andrew G. W. Leslie ◽  
Christopher G. Tate
Keyword(s):  
Hydrogen Bonds ◽  
Binding Site ◽  
G Protein ◽  
Molecular Basis ◽  
Agonist Binding ◽  
High Affinity ◽  
Protein Ligand Interactions ◽  
Wide Range ◽  
Ligand Interactions ◽  
G Protein Coupled

AbstractA characteristic of GPCRs in the G protein-coupled state is that the affinity of the agonist often increases significantly, but the molecular basis for this is unclear. We have determined six active-state structures of the β1-adrenoceptor (β1AR) bound to conformation-specific nanobodies in the presence of agonists of varying efficacy. A direct comparison with structures of β1AR in inactive states bound to the identical ligands showed a 24-42% reduction in the volume of the orthosteric binding site. Potential hydrogen bonds were also shorter, and there was up to a 30% increase in the number of atomic contacts between the receptor and ligand. GPCRs are highly conserved, so these factors will likely be essential in increasing the affinity of a wide range of structurally distinct agonists.One Sentence SummaryHigh affinity agonist binding to G protein-coupled GPCRs results from an increase in the number and strength of protein-ligand interactions.

scholarly journals Molecular basis for high-affinity agonist binding in GPCRs

Science ◽  
2019 ◽  
Vol 364 (6442) ◽  
pp. 775-778 ◽  
Author(s):  
Tony Warne ◽  
Patricia C. Edwards ◽  
Andrew S. Doré ◽  
Andrew G. W. Leslie ◽  
Christopher G. Tate
Keyword(s):  
Hydrogen Bonds ◽  
G Protein ◽  
Molecular Basis ◽  
G Protein Coupled Receptors ◽  
Active State ◽  
Agonist Binding ◽  
Inactive State ◽  
High Affinity ◽  
Wide Range ◽  
G Protein Coupled

G protein–coupled receptors (GPCRs) in the G protein–coupled active state have higher affinity for agonists as compared with when they are in the inactive state, but the molecular basis for this is unclear. We have determined four active-state structures of the β1-adrenoceptor (β1AR) bound to conformation-specific nanobodies in the presence of agonists of varying efficacy. Comparison with inactive-state structures of β1AR bound to the identical ligands showed a 24 to 42% reduction in the volume of the orthosteric binding site. Potential hydrogen bonds were also shorter, and there was up to a 30% increase in the number of atomic contacts between the receptor and ligand. This explains the increase in agonist affinity of GPCRs in the active state for a wide range of structurally distinct agonists.

Molecular basis of G protein-coupled receptor high affinity for gastrin-releasing peptide (GRP)

2003 ◽  
Vol 124 (4) ◽  
pp. A469
Author(s):  
Tomoo Nakagawa ◽  
Jose A. Tapia ◽  
Kenji Tokita ◽  
Samuel Mantey ◽  
Michael Schumann ◽  
...  
Keyword(s):  
G Protein ◽  
Molecular Basis ◽  
G Protein Coupled Receptor ◽  
Gastrin Releasing Peptide ◽  
High Affinity ◽  
G Protein Coupled

scholarly journals G Protein-Coupled Receptors in Taste Physiology and Pharmacology

2020 ◽  
Vol 11 ◽  
Author(s):  
Raise Ahmad ◽  
Julie E. Dalziel
Keyword(s):  
Binding Site ◽  
G Protein ◽  
Molecular Mechanisms ◽  
Taste Receptor ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Type I ◽  
Taste Receptors ◽  
Agonist Binding ◽  
G Protein Coupled

Heterotrimeric G protein-coupled receptors (GPCRs) comprise the largest receptor family in mammals and are responsible for the regulation of most physiological functions. Besides mediating the sensory modalities of olfaction and vision, GPCRs also transduce signals for three basic taste qualities of sweet, umami (savory taste), and bitter, as well as the flavor sensation kokumi. Taste GPCRs reside in specialised taste receptor cells (TRCs) within taste buds. Type I taste GPCRs (TAS1R) form heterodimeric complexes that function as sweet (TAS1R2/TAS1R3) or umami (TAS1R1/TAS1R3) taste receptors, whereas Type II are monomeric bitter taste receptors or kokumi/calcium-sensing receptors. Sweet, umami and kokumi receptors share structural similarities in containing multiple agonist binding sites with pronounced selectivity while most bitter receptors contain a single binding site that is broadly tuned to a diverse array of bitter ligands in a non-selective manner. Tastant binding to the receptor activates downstream secondary messenger pathways leading to depolarization and increased intracellular calcium in TRCs, that in turn innervate the gustatory cortex in the brain. Despite recent advances in our understanding of the relationship between agonist binding and the conformational changes required for receptor activation, several major challenges and questions remain in taste GPCR biology that are discussed in the present review. In recent years, intensive integrative approaches combining heterologous expression, mutagenesis and homology modeling have together provided insight regarding agonist binding site locations and molecular mechanisms of orthosteric and allosteric modulation. In addition, studies based on transgenic mice, utilizing either global or conditional knock out strategies have provided insights to taste receptor signal transduction mechanisms and their roles in physiology. However, the need for more functional studies in a physiological context is apparent and would be enhanced by a crystallized structure of taste receptors for a more complete picture of their pharmacological mechanisms.

scholarly journals Structural Requirements for the Activation of the Human Growth Hormone Secretagogue Receptor by Peptide and Nonpeptide Secretagogues

1998 ◽  
Vol 12 (1) ◽  
pp. 137-145 ◽  
Author(s):  
Scott D. Feighner ◽  
Andrew D. Howard ◽  
Kristine Prendergast ◽  
Oksana C. Palyha ◽  
Donna L. Hreniuk ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Binding Site ◽  
G Protein ◽  
Human Growth ◽  
G Protein Coupled Receptors ◽  
Site Directed Mutagenesis ◽  
Agonist Binding ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
G Protein Coupled

Abstract Antibodies raised against an intracellular and extracellular domain of the GH secretagogue receptor (GHS-R) confirmed that its topological orientation in the lipid bilayer is as predicted for G protein-coupled receptors with seven transmembrane domains. A strategy for mapping the agonist-binding site of the human GHS-R was conceived based on our understanding of ligand binding in biogenic amine and peptide hormone G protein-coupled receptors. Using site-directed mutagenesis and molecular modeling, we classified GHS peptide and nonpeptide agonist binding in the context of its receptor environment. All peptide and nonpeptide ligand classes shared a common binding domain in transmembrane (TM) region 3 of the GHS-R. This finding was based on TM-3 mutation E124Q, which eliminated the counter-ion to the shared basic N+ group of all GHSs and resulted in a nonfunctional receptor. Restoration of function for the E124Q mutant was achieved by a complementary change in the MK-0677 ligand through modification of its amine side-chain to the corresponding alcohol. Contacts in other TM domains [TM-2 (D99N), TM-5 (M213K, S117A), TM-6 (H280F), and extracellular loop 1 (C116A)] of the receptor revealed specificity for the different peptide, benzolactam, and spiroindolane GHSs. GHS-R agonism, therefore, does not require identical disposition of all agonist classes at the ligand-binding site. Our results support the hypothesis that the ligand-binding pocket in the GHS-R is spatially disposed similarly to the well characterized catechol-binding site in theβ 2-adrenergic receptor.

scholarly journals The N-Terminal Juxtamembrane Segment of the V1a Vasopressin Receptor Provides Two Independent Epitopes Required for High-Affinity Agonist Binding and Signaling

2005 ◽  
Vol 19 (11) ◽  
pp. 2871-2881 ◽  
Author(s):  
Stuart R. Hawtin ◽  
Victoria J. Wesley ◽  
John Simms ◽  
Cymone C. H. Argent ◽  
Khalid Latif ◽  
...  
Keyword(s):  
G Protein ◽  
Arginine Vasopressin ◽  
Transmembrane Helix ◽  
Receptor Interaction ◽  
Vasopressin Receptor ◽  
Agonist Binding ◽  
Alanine Scanning Mutagenesis ◽  
High Affinity ◽  
Antagonist Binding ◽  
G Protein Coupled

Abstract It is fundamentally important to define how agonist-receptor interaction differs from antagonist-receptor interaction. The V1a vasopressin receptor (V1aR) is a member of the neurohypophysial hormone subfamily of G protein-coupled receptors. Using alanine-scanning mutagenesis of the N-terminal juxtamembrane segment of the V1aR, we now establish that Glu54 (1.35) is critical for arginine vasopressin binding. The mutant [E54A]V1aR exhibited decreased arginine vasopressin affinity (1700-fold) and disrupted signaling, but antagonist binding was unaffected. Mutation of Glu54 had an almost identical pharmacological effect as mutation of Arg46, raising the possibility that agonist binding required a mutual interaction between Glu54 and Arg46. The role of these two charged residues was investigated by 1) substituting Glu54; 2) inserting additional Glu/Arg in transmembrane helix (TM) 1; 3) repositioning the Glu/Arg in TM1; and 4) characterizing the reciprocal mutant [R46E/E54R]V1aR. We conclude that 1) the positive/negative charges need to be precisely positioned in this N terminus/TM1 segment; and 2) Glu54 and Arg46 function independently, providing two discrete epitopes required for high-affinity agonist binding and signaling. This study explains why Glu and Arg, part of an -R(X3)L/V(X3)E(X3)L- motif, are conserved at these loci throughout this G protein-coupled receptor subfamily and provides molecular insight into key differences between agonist and antagonist binding requirements.

scholarly journals Mini-review: antibody therapeutics targeting G protein-coupled receptors and ion channels

2020 ◽  
Vol 3 (4) ◽  
pp. 257-264
Author(s):  
Catherine J Hutchings
Keyword(s):  
Ion Channels ◽  
Research And Development ◽  
Small Molecules ◽  
G Protein ◽  
Clinical Studies ◽  
G Protein Coupled Receptors ◽  
Protein Targets ◽  
Antibody Therapeutics ◽  
Wide Range ◽  
G Protein Coupled

Abstract Antibodies are now well established as therapeutics with many additional advantages over small molecules and peptides relative to their selectivity, bioavailability, half-life and effector function. Major classes of membrane-associated protein targets include G protein-coupled receptors (GPCRs) and ion channels that are linked to a wide range of disease indications across all therapeutic areas. This mini-review summarizes the antibody target landscape for both GPCRs and ion channels as well as current progress in the respective research and development pipelines with some example case studies highlighted from clinical studies, including those being evaluated for the treatment of symptoms in COVID-19 infection.

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