scholarly journals Ca2+ allostery in PTH-receptor signaling

2019 ◽  
Vol 116 (8) ◽  
pp. 3294-3299 ◽  
Author(s):  
Alex D. White ◽  
Fei Fang ◽  
Frédéric G. Jean-Alphonse ◽  
Lisa J. Clark ◽  
Hyun-Jung An ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
Receptor Activation ◽  
Mass Accuracy ◽  
Camp Signaling ◽  
Allosteric Modulator ◽  
Extracellular Loop ◽  
Camp Production ◽  
Positive Allosteric Modulator ◽  
Early Endosomes ◽  
G Protein Coupled

The parathyroid hormone (PTH) and its related peptide (PTHrP) activate PTH receptor (PTHR) signaling, but only the PTH sustains GS-mediated adenosine 3′,5′-cyclic monophosphate (cAMP) production after PTHR internalization into early endosomes. The mechanism of this unexpected behavior for a G-protein–coupled receptor is not fully understood. Here, we show that extracellular Ca2+ acts as a positive allosteric modulator of PTHR signaling that regulates sustained cAMP production. Equilibrium and kinetic studies of ligand-binding and receptor activation reveal that Ca2+ prolongs the residence time of ligands on the receptor, thus, increasing both the duration of the receptor activation and the cAMP signaling. We further find that Ca2+ allostery in the PTHR is strongly affected by the point mutation recently identified in the PTH (PTHR25C) as a new cause of hypocalcemia in humans. Using high-resolution and mass accuracy mass spectrometry approaches, we identified acidic clusters in the receptor’s first extracellular loop as key determinants for Ca2+ allosterism and endosomal cAMP signaling. These findings coupled to defective Ca2+ allostery and cAMP signaling in the PTHR by hypocalcemia-causing PTHR25C suggest that Ca2+ allostery in PTHR signaling may be involved in primary signaling processes regulating calcium homeostasis.

scholarly journals The Nematode Leucine-Rich Repeat-Containing, G Protein-Coupled Receptor (LGR) Protein Homologous to Vertebrate Gonadotropin and Thyrotropin Receptors is Constitutively Activated in Mammalian Cells

2000 ◽  
Vol 14 (2) ◽  
pp. 272-284 ◽  
Author(s):  
Masataka Kudo ◽  
Thomas Chen ◽  
Koji Nakabayashi ◽  
Sheau Yu Hsu ◽  
Aaron J. W. Hsueh
Keyword(s):  
G Protein ◽  
Hormone Receptors ◽  
Receptor Activation ◽  
Leucine Rich Repeat ◽  
Camp Production ◽  
Glycoprotein Hormone ◽  
Lh Receptor ◽  
Glycoprotein Hormone Receptors ◽  
Leucine Rich Repeats ◽  
G Protein Coupled

Abstract The receptors for LH, FSH, and TSH belong to the large G protein-coupled, seven-transmembrane (TM) protein family and are unique in having a large N-terminal extracellular (ecto-) domain containing leucine-rich repeats important for interactions with the large glycoprotein hormone ligands. Recent studies indicated the evolution of an expanding family of homologous leucine-rich repeat-containing, G protein-coupled receptors (LGRs), including the three known glycoprotein hormone receptors; mammalian LGR4 and LGR5; and LGRs in sea anemone, fly, and snail. We isolated nematode LGR cDNA and characterized its gene from the Caenorhabditis elegans genome. This receptor cDNA encodes 929 amino acids consisting of a signal peptide for membrane insertion, an ectodomain with nine leucine-rich repeats, a seven-TM region, and a long C-terminal tail. The nematode LGR has five potential N-linked glycosylation sites in its ectodomain and multiple consensus phosphorylation sites for protein kinase A and C in the cytoplasmic loop and C tail. The nematode receptor gene has 13 exons; its TM region and C tail, unlike mammalian glycoprotein hormone receptors, are encoded by multiple exons. Sequence alignments showed that the TM region of the nematode receptor has 30% identity and 50% similarity to the same region in mammalian glycoprotein hormone receptors. Although human 293T cells expressing the nematode LGR protein do not respond to human glycoprotein hormones, these cells exhibited major increases in basal cAMP production in the absence of ligand stimulation, reaching levels comparable to those in cells expressing a constitutively activated mutant human LH receptor found in patients with familial male-limited precocious puberty. Analysis of cAMP production mediated by chimeric receptors further indicated that the ectodomain and TM region of the nematode LGR and human LH receptor are interchangeable and the TM region of the nematode LGR is responsible for constitutive receptor activation. Thus, the identification and characterization of the nematode receptor provides the basis for understanding the evolutionary relationship of diverse LGRs and for future analysis of mechanisms underlying the activation of glycoprotein hormone receptors and related LGRs.

scholarly journals Mechanism of β2AR regulation by an intracellular positive allosteric modulator

Science ◽  
2019 ◽  
Vol 364 (6447) ◽  
pp. 1283-1287 ◽  
Author(s):  
Xiangyu Liu ◽  
Ali Masoudi ◽  
Alem W. Kahsai ◽  
Li-Yin Huang ◽  
Biswaranjan Pani ◽  
...  
Keyword(s):  
G Protein ◽  
Adrenergic Receptor ◽  
Helical Conformation ◽  
Allosteric Modulator ◽  
Intracellular Loop ◽  
Positive Allosteric Modulator ◽  
Transmembrane Segments ◽  
Allosteric Binding Sites ◽  
Loop 2 ◽  
G Protein Coupled

Drugs targeting the orthosteric, primary binding site of G protein–coupled receptors are the most common therapeutics. Allosteric binding sites, elsewhere on the receptors, are less well-defined, and so less exploited clinically. We report the crystal structure of the prototypic β2-adrenergic receptor in complex with an orthosteric agonist and compound-6FA, a positive allosteric modulator of this receptor. It binds on the receptor’s inner surface in a pocket created by intracellular loop 2 and transmembrane segments 3 and 4, stabilizing the loop in an α-helical conformation required to engage the G protein. Structural comparison explains the selectivity of the compound for β2- over the β1-adrenergic receptor. Diversity in location, mechanism, and selectivity of allosteric ligands provides potential to expand the range of receptor drugs.

scholarly journals Contact inhibitory Eph signaling suppresses EGF-promoted cell migration by decoupling EGFR activity from vesicular recycling

2017 ◽  
Author(s):  
Wayne Stallaert ◽  
Ola Sabet ◽  
Yannick Brüggemann ◽  
Lisa Baak ◽  
Philippe I.H. Bastiaens
Keyword(s):  
Cellular Response ◽  
Receptor Activation ◽  
Vesicular Trafficking ◽  
Eph Receptor ◽  
Extracellular Signals ◽  
Cellular Environment ◽  
Egfr Activation ◽  
Early Endosomes ◽  
Context Dependent ◽  
G Protein Coupled

AbstractThe ability of cells to adapt their behavior to growth factors in relation to their environment is an essential aspect of tissue development and homeostasis. Here we show that Eph receptor signaling from cell-cell contacts changes the cellular response to EGFR activation by altering its vesicular trafficking. Eph receptor activation traps EGFR in Rab5-positive early endosomes through an inhibition of Akt-dependent vesicular recycling. By altering the spatial distribution of EGFR activity during EGF stimulation, Eph receptor activation selectively suppresses migratory Akt signaling from the plasma membrane, while preserving proliferative ERK signaling from endosomes. We also show that soluble extracellular signals engaging the G-protein coupled receptor Kiss1 similarly suppress vesicular recycling to alter EGFR signaling. The cellular environment can thus modulate EGFR vesicular trafficking dynamics to generate context-dependent responses to EGF stimulation.SummaryEph receptor activation generates context-dependent cellular responses to EGFR activation by altering its vesicular trafficking dynamics.

scholarly journals The role of ECL2 in CGRP receptor activation: a combined modelling and experimental approach

2013 ◽  
Vol 10 (88) ◽  
pp. 20130589 ◽  
Author(s):  
Michael. J. Woolley ◽  
Harriet A. Watkins ◽  
Bruck Taddese ◽  
Z. Gamze Karakullukcu ◽  
James Barwell ◽  
...  
Keyword(s):  
Experimental Approach ◽  
Point Mutations ◽  
Receptor Activation ◽  
Calcitonin Receptor ◽  
Extracellular Loop ◽  
Cgrp Receptor ◽  
Alanine Scan ◽  
Calcitonin Gene ◽  
G Protein Coupled

The calcitonin gene-related peptide (CGRP) receptor is a complex of a calcitonin receptor-like receptor (CLR), which is a family B G-protein-coupled receptor (GPCR) and receptor activity modifying protein 1. The role of the second extracellular loop (ECL2) of CLR in binding CGRP and coupling to Gs was investigated using a combination of mutagenesis and modelling. An alanine scan of residues 271–294 of CLR showed that the ability of CGRP to produce cAMP was impaired by point mutations at 13 residues; most of these also impaired the response to adrenomedullin (AM). These data were used to select probable ECL2-modelled conformations that are involved in agonist binding, allowing the identification of the likely contacts between the peptide and receptor. The implications of the most likely structures for receptor activation are discussed.

scholarly journals Crystal structure of the human oxytocin receptor

2020 ◽  
Vol 6 (29) ◽  
pp. eabb5419 ◽  
Author(s):  
Yann Waltenspühl ◽  
Jendrik Schöppe ◽  
Janosch Ehrenmann ◽  
Lutz Kummer ◽  
Andreas Plückthun
Keyword(s):  
Crystal Structure ◽  
Preterm Labor ◽  
Peptide Hormone ◽  
Oxytocin Receptor ◽  
Oral Drug ◽  
Allosteric Modulator ◽  
Agonist Binding ◽  
Positive Allosteric Modulator ◽  
G Protein Coupled ◽  
Receptor Family

The peptide hormone oxytocin modulates socioemotional behavior and sexual reproduction via the centrally expressed oxytocin receptor (OTR) across several species. Here, we report the crystal structure of human OTR in complex with retosiban, a nonpeptidic antagonist developed as an oral drug for the prevention of preterm labor. Our structure reveals insights into the detailed interactions between the G protein–coupled receptor (GPCR) and an OTR-selective antagonist. The observation of an extrahelical cholesterol molecule, binding in an unexpected location between helices IV and V, provides a structural rationale for its allosteric effect and critical influence on OTR function. Furthermore, our structure in combination with experimental data allows the identification of a conserved neurohypophyseal receptor-specific coordination site for Mg2+ that acts as potent, positive allosteric modulator for agonist binding. Together, these results further our molecular understanding of the oxytocin/vasopressin receptor family and will facilitate structure-guided development of new therapeutics.

Potentiation of muscarinic M3 receptor activation through a new allosteric site with a novel positive allosteric modulator ASP8302

2021 ◽  
pp. JPET-AR-2021-000709
Author(s):  
Risa Okimoto ◽  
Katsutoshi Ino ◽  
Kenichiro Ishizu ◽  
Hajime Takamatsu ◽  
Kazuyuki Sakamoto ◽  
...  
Keyword(s):  
Receptor Activation ◽  
Allosteric Modulator ◽  
Allosteric Site ◽  
Positive Allosteric Modulator ◽  
M3 Receptor

scholarly journals Members of the KCTD family are major regulators of cAMP signaling

2021 ◽  
Vol 119 (1) ◽  
pp. e2119237119
Author(s):  
Brian S. Muntean ◽  
Subhi Marwari ◽  
Xiaona Li ◽  
Douglas C. Sloan ◽  
Brian D. Young ◽  
...  
Keyword(s):  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Camp Signaling ◽  
Motor Deficits ◽  
Adenylyl Cyclases ◽  
Striatal Neurons ◽  
Camp Production ◽  
Neuronal Function ◽  
Signaling Systems ◽  
G Protein Coupled

Cyclic adenosine monophosphate (cAMP) is a pivotal second messenger with an essential role in neuronal function. cAMP synthesis by adenylyl cyclases (AC) is controlled by G protein–coupled receptor (GPCR) signaling systems. However, the network of molecular players involved in the process is incompletely defined. Here, we used CRISPR/Cas9–based screening to identify that members of the potassium channel tetradimerization domain (KCTD) family are major regulators of cAMP signaling. Focusing on striatal neurons, we show that the dominant isoform KCTD5 exerts its effects through an unusual mechanism that modulates the influx of Zn2+ via the Zip14 transporter to exert unique allosteric effects on AC. We further show that KCTD5 controls the amplitude and sensitivity of stimulatory GPCR inputs to cAMP production by Gβγ-mediated AC regulation. Finally, we report that KCTD5 haploinsufficiency in mice leads to motor deficits that can be reversed by chelating Zn2+. Together, our findings uncover KCTD proteins as major regulators of neuronal cAMP signaling via diverse mechanisms.

scholarly journals Crystal structure of the human oxytocin receptor

2020 ◽  
Author(s):  
Yann Waltenspühl ◽  
Jendrik Schöppe ◽  
Janosch Ehrenmann ◽  
Lutz Kummer ◽  
Andreas Plückthun
Keyword(s):  
Crystal Structure ◽  
Preterm Labour ◽  
Peptide Hormone ◽  
Oxytocin Receptor ◽  
Oral Drug ◽  
Allosteric Modulator ◽  
Agonist Binding ◽  
Positive Allosteric Modulator ◽  
G Protein Coupled ◽  
Receptor Family

AbstractThe peptide hormone oxytocin modulates socioemotional behaviour and sexual reproduction via the centrally expressed oxytocin receptor (OTR) across several species. Here, we report the crystal structure of human OTR in complex with retosiban, a non-peptide antagonist developed as an oral drug for the prevention of preterm labour. Our structure reveals insights into the detailed interactions between the G-protein coupled receptor (GPCR) and an OTR-selective antagonist. The observation of an extrahelical cholesterol molecule, binding in an unexpected location between helix IV and V, provides a structural rationale for its allosteric effect and critical influence on OTR function. Furthermore, our structure in combination with experimental data allows the identification of a conserved neurohypophyseal receptor-specific coordination site for Mg2+ that acts as potent positive allosteric modulator for agonist binding. Together these results further our molecular understanding of the oxytocin/vasopressin receptor family and will facilitate structure-guided development of new therapeutics.

scholarly journals A nanobody activating metabotropic glutamate receptor 4 discriminates between homo- and heterodimers

2021 ◽  
Vol 118 (33) ◽  
pp. e2105848118
Author(s):  
Jordi Haubrich ◽  
Joan Font ◽  
Robert B. Quast ◽  
Anne Goupil-Lamy ◽  
Pauline Scholler ◽  
...  
Keyword(s):  
Small Molecules ◽  
Metabotropic Glutamate Receptor ◽  
Brain Diseases ◽  
Allosteric Modulator ◽  
Receptor Subtypes ◽  
Positive Allosteric Modulator ◽  
Metabotropic Glutamate ◽  
Glutamate Binding ◽  
Subtype Selective ◽  
G Protein Coupled

There is growing interest in developing biologics due to their high target selectivity. The G protein–coupled homo- and heterodimeric metabotropic glutamate (mGlu) receptors regulate many synapses and are promising targets for the treatment of numerous brain diseases. Although subtype-selective allosteric small molecules have been reported, their effects on the recently discovered heterodimeric receptors are often not known. Here, we describe a nanobody that specifically and fully activates homodimeric human mGlu4 receptors. Molecular modeling and mutagenesis studies revealed that the nanobody acts by stabilizing the closed active state of the glutamate binding domain by interacting with both lobes. In contrast, this nanobody does not activate the heterodimeric mGlu2-4 but acts as a pure positive allosteric modulator. These data further reveal how an antibody can fully activate a class C receptor and bring further evidence that nanobodies represent an alternative way to specifically control mGlu receptor subtypes.

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