scholarly journals Ligand recognition, unconventional activation, and G protein coupling of the prostaglandin E2 receptor EP2 subtype

2021 ◽  
Vol 7 (14) ◽  
pp. eabf1268
Author(s):  
Changxiu Qu ◽  
Chunyou Mao ◽  
Peng Xiao ◽  
Qingya Shen ◽  
Ya-Ni Zhong ◽  
...  
Keyword(s):  
G Protein ◽  
Rational Design ◽  
Receptor Activation ◽  
Prostaglandin E ◽  
Toggle Switch ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
Ligand Selectivity ◽  
Activation Mechanisms ◽  
Prostaglandin E2 Receptor

Selective modulation of the heterotrimeric G protein α S subunit–coupled prostaglandin E2 (PGE2) receptor EP2 subtype is a promising therapeutic strategy for osteoporosis, ocular hypertension, neurodegenerative diseases, and cardiovascular disorders. Here, we report the cryo–electron microscopy structure of the EP2-Gs complex with its endogenous agonist PGE2 and two synthesized agonists, taprenepag and evatanepag (CP-533536). These structures revealed distinct features of EP2 within the EP receptor family in terms of its unconventional receptor activation and G protein coupling mechanisms, including activation in the absence of a typical W6.48 “toggle switch” and coupling to Gs via helix 8. Moreover, inspection of the agonist-bound EP2 structures uncovered key motifs governing ligand selectivity. Our study provides important knowledge for agonist recognition and activation mechanisms of EP2 and will facilitate the rational design of drugs targeting the PGE2 signaling system.

scholarly journals Receptor-wide Determinants of G Protein Coupling Selectivity in Aminergic GPCRs

2021 ◽  
Author(s):  
Berkay Selçuk ◽  
Ismail Erol ◽  
Serdar Durdağı ◽  
Ogun Adebali
Keyword(s):  
Ligand Binding ◽  
G Protein ◽  
Md Simulations ◽  
Binding Pocket ◽  
Receptor Activation ◽  
Selective Activation ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
Gpcr Activation ◽  
Activation Mechanisms

AbstractG protein-coupled receptors (GPCRs) induce signal transduction pathways through coupling to four main subtypes of G proteins (Gs, Gi, Gq, G12/13), selectively. However, G protein selective activation mechanisms and residual determinants in GPCRs have remained obscure. Here, we identified conserved G protein selective activation mechanisms determining receptors’ ability to couple to a type of G protein. Herein, we performed an extensive phylogenetic analysis and identified specifically conserved residues for the receptors having similar coupling profiles in each aminergic receptor. By integrating our methodology of differential evolutionary conservation of G protein-specific amino acids with structural analyses, we identified selective activation networks for Gs, Gi1, Go, and Gq. We found that G protein selectivity is determined by not only the G protein interaction site but also other parts of the receptor including the ligand binding pocket. To validate our findings, we further studied an amino acid residue that we revealed as a selectivity-determining in Gs coupling and performed molecular dynamics (MD) simulations. We showed that previously uncharacterized Glycine at position 7×41 plays an important role in both receptor activation and Gs coupling. Finally, we gathered our results into a comprehensive model of G protein selectivity called “sequential switches of activation” describing three main molecular switches controlling GPCR activation: ligand binding, G protein selective activation mechanisms and G protein contact. We believe that our work provides a broader view on receptor-level determinants of G protein coupling selectivity.

G Protein Coupling and Ligand Selectivity of the D2L and D3 Dopamine Receptors

2008 ◽  
Vol 325 (1) ◽  
pp. 319-330 ◽  
Author(s):  
J. Robert Lane ◽  
Ben Powney ◽  
Alan Wise ◽  
Stephen Rees ◽  
Graeme Milligan
Keyword(s):  
Dopamine Receptors ◽  
G Protein ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
Ligand Selectivity

scholarly journals The Glycosphingolipid GM3 Modulates Conformational Dynamics of the Glucagon Receptor

2020 ◽  
Author(s):  
T. Bertie Ansell ◽  
Wanling Song ◽  
Mark S. P. Sansom
Keyword(s):  
Molecular Dynamics ◽  
G Protein ◽  
Transmembrane Domain ◽  
Conformational Dynamics ◽  
Extracellular Domain ◽  
Receptor Activation ◽  
G Protein Coupling ◽  
Glucagon Receptor ◽  
Protein Coupling ◽  
Class A

AbstractThe extracellular domain (ECD) of Class B1 G-protein coupled receptors (GPCRs) plays a central role in signal transduction and is uniquely positioned to sense both the extracellular and membrane environments. Whilst recent studies suggest a role for membrane lipids in the modulation of Class A and Class F GPCR signalling properties, little is known about the effect of lipids on Class B1 receptors. In this study, we employed multiscale molecular dynamics (MD) simulations to access the dynamics of the glucagon receptor (GCGR) ECD in the presence of native-like membrane bilayers. Simulations showed that the ECD could move about a hinge region formed by residues Q122-E126 to adopt both closed and open conformations relative to the TMD. ECD movements were modulated by binding of the glycosphingolipid GM3. These large-scale fluctuations in ECD conformation that may affect the ligand binding and receptor activation properties. We also identify a unique PIP2 interaction profile near ICL2/TM3 at the G-protein coupling interface, suggesting a mechanism of engaging G-proteins which may have a distinct dependence on PIP2 compared to Class A GPCRs. Given the structural conservation of Class B1 GPCRs, the modulatory effects of GM3 and PIP2 on GCGR may be conserved across these receptors, offering new insights into potential therapeutic targeting.Statement of SignificanceThe role of lipids in regulation of Class B GPCRs remains elusive, despite recent structural advances. In this study, multi-scale molecular dynamics simulations are used to evaluate lipid interactions with the glucagon receptor, a Class B1 GPCR. We find that the glycosphingolipid GM3 binds to the glucagon receptor extracellular domain (ECD), modulating the dynamics of the ECD and promoting movement away from the transmembrane domain. We also identify a unique PIP2 interaction fingerprint in a region known to be important for bridging G-protein coupling in Class A GPCRs. Thus, this study provides molecular insight into the behaviour of the glucagon receptor in a complex lipid bilayer environment which may aid understanding of glucagon receptor signalling properties.

scholarly journals Biochemical characterization of G protein coupling to calcitonin gene–related peptide and adrenomedullin receptors using a native PAGE assay

2020 ◽  
Vol 295 (28) ◽  
pp. 9736-9751 ◽  
Author(s):  
Amanda M. Roehrkasse ◽  
Margaret L. Warner ◽  
Jason M. Booe ◽  
Augen A. Pioszak
Keyword(s):  
G Protein ◽  
Mammalian Cells ◽  
Calcitonin Gene Related Peptide ◽  
Peptide Ligand ◽  
Native Page ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
Ligand Selectivity ◽  
Related Peptide ◽  
Calcitonin Gene

Calcitonin gene-related peptide (CGRP), adrenomedullin (AM), and adrenomedullin 2/intermedin (AM2/IMD) have overlapping and unique functions in the nervous and circulatory systems including vasodilation, cardioprotection, and pain transmission. Their actions are mediated by the class B calcitonin-like G protein–coupled receptor (CLR), which heterodimerizes with three receptor activity–modifying proteins (RAMP1–3) that determine its peptide ligand selectivity. How the three agonists and RAMPs modulate CLR binding to transducer proteins remains poorly understood. Here, we biochemically characterized agonist-promoted G protein coupling to each CLR·RAMP complex. We adapted a native PAGE method to assess the formation and thermostabilities of detergent-solubilized fluorescent protein–tagged CLR·RAMP complexes expressed in mammalian cells. Addition of agonist and the purified Gs protein surrogate mini-Gs (mGs) yielded a mobility-shifted agonist·CLR·RAMP·mGs quaternary complex gel band that was sensitive to antagonists. Measuring the apparent affinities of the agonists for the mGs-coupled receptors and of mGs for the agonist-occupied receptors revealed that both ligand and RAMP control mGs coupling and defined how agonist engagement of the CLR extracellular and transmembrane domains affects transducer recruitment. Using mini-Gsq and -Gsi chimeras, we observed a coupling rank order of mGs > mGsq > mGsi for each receptor. Last, we demonstrated the physiological relevance of the native gel assays by showing that they can predict the cAMP-signaling potencies of AM and AM2/IMD chimeras. These results highlight the power of the native PAGE assay for membrane protein biochemistry and provide a biochemical foundation for understanding the molecular basis of shared and distinct signaling properties of CGRP, AM, and AM2/IMD.

Tempol reduces oxidative stress and restores renal dopamine D1-like receptor- G protein coupling and function in hyperglycemic rats

2006 ◽  
Vol 291 (1) ◽  
pp. F58-F66 ◽  
Author(s):  
Aditi Marwaha ◽  
Mustafa F. Lokhandwala
Keyword(s):  
Oxidative Stress ◽  
G Protein ◽  
Sodium Excretion ◽  
Receptor Activation ◽  
Serine Phosphorylation ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
Agonist Stimulation ◽  
Renal Dopamine ◽  
And Function

Dopamine via activation of renal D1-like receptors inhibits the activities of Na-K-ATPase and Na/H exchanger and subsequently increases sodium excretion. Decreased renal dopamine production and sodium excretion are associated with hyperglycemic conditions. We have earlier reported D1-like receptor-G protein uncoupling and reduced response to D1-like receptor activation in streptozotocin (STZ)-treated hyperglycemic rats (Marwaha A, Banday AA, and Lokhandwala MF. Am J Physiol Renal Physiol 286: F451–F457, 2004). The present study was designed to test the hypothesis that oxidative stress associated with hyperglycemia increases basal D1-like receptor serine phosphorylation via activation of the PKC-G protein receptor kinase (GRK) pathway, resulting in loss of D1-like receptor-G protein coupling and function. We observed that STZ-treated rats exhibited oxidative stress as evidenced by increased lipid peroxidation. Furthermore, PKC activity and expression of PKC-βI- and -δ-isoforms were increased in STZ-treated rats. In addition, in STZ-treated rats there was increased GRK2 translocation to proximal tubular membrane and increased basal serine D1-like receptor phosphorylation. Supplementation with the antioxidant tempol lowered oxidative stress in STZ-treated rats, led to normalization of PKC activity, and prevented GRK2 translocation. Furthermore, tempol supplementation in STZ-treated rats restored D1-like receptor-G protein coupling and inhibition of Na-K-ATPase activity on D1-like receptor agonist stimulation. The functional consequence was the restoration of the natriuretic response to D1-like receptor activation. We conclude that oxidative stress associated with hyperglycemia causes an increase in activity and expression of PKC. This leads to translocation of GRK2, subsequent phosphorylation of the D1-like receptor, its uncoupling from G proteins and loss of responsiveness to agonist stimulation.

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