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.

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.

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 Picomolar affinity antagonist and sustained signaling agonist peptide ligands for the adrenomedullin and calcitonin gene-related peptide receptors

2020 ◽  
Author(s):  
Jason M. Booe ◽  
Margaret L. Warner ◽  
Augen A. Pioszak
Keyword(s):  
Drug Targets ◽  
Rational Design ◽  
Transmembrane Domain ◽  
Calcitonin Gene Related Peptide ◽  
Peptide Ligands ◽  
Ligand Selectivity ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
Receptor Activity Modifying Proteins ◽  
Long Acting

AbstractThe calcitonin receptor-like G protein-coupled receptor (CLR) mediates adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) actions including vasodilation, cardioprotection, and nociception. Receptor activity-modifying proteins (RAMP1-3) determine CLR ligand selectivity through an unresolved mechanism. CLR-RAMP complexes are drug targets, but short AM and CGRP plasma half-lives limit their therapeutic utility. We used combinatorial peptide library and rational design approaches to probe selectivity determinants and develop short AM and CGRP variants with ∼1000-fold increased receptor extracellular domain affinities. Binding and structural studies explained the increased affinities and defined roles for AM Lys46 and RAMP modulation of CLR conformation in selectivity. In longer scaffolds that also bind the CLR transmembrane domain the variants generated picomolar affinity antagonists, one with an estimated 12.5 hr CGRP receptor residence time, and sustained signaling agonists ss-AM and ss-CGRP. This work clarifies the RAMP-modulated ligand selectivity mechanism and provides AM and CGRP variants with promise as long-acting therapeutics.

scholarly journals The Specificity of Downstream Signaling for A1 and A2AR Does Not Depend on the C-Terminus, Despite the Importance of This Domain in Downstream Signaling Strength

Biomedicines ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 603
Author(s):  
Abhinav R. Jain ◽  
Claire McGraw ◽  
Anne S. Robinson
Keyword(s):  
Crystal Structures ◽  
G Protein ◽  
Mammalian Cells ◽  
Full Length ◽  
Surprising Result ◽  
G Protein Coupling ◽  
Hek 293 ◽  
Protein Coupling ◽  
Downstream Signaling ◽  
C Terminus

Recent efforts to determine the high-resolution crystal structures for the adenosine receptors (A1R and A2AR) have utilized modifications to the native receptors in order to facilitate receptor crystallization and structure determination. One common modification is a truncation of the unstructured C-terminus, which has been utilized for all the adenosine receptor crystal structures obtained to date. Ligand binding for this truncated receptor has been shown to be similar to full-length receptor for A2AR. However, the C-terminus has been identified as a location for protein-protein interactions that may be critical for the physiological function of these important drug targets. We show that variants with A2AR C-terminal truncations lacked cAMP-linked signaling compared to the full-length receptor constructs transfected into mammalian cells (HEK-293). In addition, we show that in a humanized yeast system, the absence of the full-length C-terminus affected downstream signaling using a yeast MAPK response-based fluorescence assay, though full-length receptors showed native-like G-protein coupling. To further study the G protein coupling, we used this humanized yeast platform to explore coupling to human-yeast G-protein chimeras in a cellular context. Although the C-terminus was essential for Gα protein-associated signaling, chimeras of A1R with a C-terminus of A2AR coupled to the A1R-specific Gα (i.e., Gαi1 versus Gαs). This surprising result suggests that the C-terminus is important in the signaling strength, but not specificity, of the Gα protein interaction. This result has further implications in drug discovery, both in enabling the experimental use of chimeras for ligand design, and in the cautious interpretation of structure-based drug design using truncated receptors.

scholarly journals Similarity between class A and class B G-protein-coupled receptors exemplified through calcitonin gene-related peptide receptor modelling and mutagenesis studies

2013 ◽  
Vol 10 (79) ◽  
pp. 20120846 ◽  
Author(s):  
Shabana Vohra ◽  
Bruck Taddese ◽  
Alex C. Conner ◽  
David R. Poyner ◽  
Debbie L. Hay ◽  
...  
Keyword(s):  
G Protein ◽  
Calcitonin Gene Related Peptide ◽  
G Protein Coupled Receptors ◽  
Cgrp Receptor ◽  
Conserved Residues ◽  
Related Peptide ◽  
Class A ◽  
Calcitonin Gene ◽  
Class B ◽  
G Protein Coupled

Modelling class B G-protein-coupled receptors (GPCRs) using class A GPCR structural templates is difficult due to lack of homology. The plant GPCR, GCR1, has homology to both class A and class B GPCRs. We have used this to generate a class A–class B alignment, and by incorporating maximum lagged correlation of entropy and hydrophobicity into a consensus score, we have been able to align receptor transmembrane regions. We have applied this analysis to generate active and inactive homology models of the class B calcitonin gene-related peptide (CGRP) receptor, and have supported it with site-directed mutagenesis data using 122 CGRP receptor residues and 144 published mutagenesis results on other class B GPCRs. The variation of sequence variability with structure, the analysis of polarity violations, the alignment of group-conserved residues and the mutagenesis results at 27 key positions were particularly informative in distinguishing between the proposed and plausible alternative alignments. Furthermore, we have been able to associate the key molecular features of the class B GPCR signalling machinery with their class A counterparts for the first time. These include the [K/R]KLH motif in intracellular loop 1, [I/L]xxxL and KxxK at the intracellular end of TM5 and TM6, the NPXXY/VAVLY motif on TM7 and small group-conserved residues in TM1, TM2, TM3 and TM7. The equivalent of the class A DRY motif is proposed to involve Arg 2.39 , His 2.43 and Glu 3.46 , which makes a polar lock with T 6.37 . These alignments and models provide useful tools for understanding class B GPCR function.

Multiple affinity and guanine nucleotide sensitive forms of the calcitonin gene related peptide (CGRP) receptor

1995 ◽  
Vol 73 (7) ◽  
pp. 968-973 ◽  
Author(s):  
Tapan K. Chatterjee ◽  
Rory A. Fisher
Keyword(s):  
G Protein ◽  
Conformational Changes ◽  
Ternary Complex ◽  
Protein S ◽  
Calcitonin Gene Related Peptide ◽  
Cgrp Receptor ◽  
Peripheral Tissues ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
G Protein Coupled

Calcitonin gene related peptide (CGRP) is a novel neuropeptide with an impressive array of biological actions consistent with its diverse tissue distribution and suggested role as neurotransmitter or neuromodulator. Binding sites for CGRP with properties consistent with those of receptors are present in both central and peripheral tissues. Radioligand binding studies were performed to investigate the fundamental processes underlying CGRP receptor activation and signaling following agonist occupancy of the receptor. These studies documented the existence of a selective, high affinity, and homogeneous population of binding sites for CGRP in membranes prepared from central and various peripheral tissues. The affinity of [125I]CGRP for these sites was regulated by GTP or its stable analog GTPγS, indicating coupling of CGRP receptors to G-protein(s). Kinetic studies documented the existence of the CGRP receptor in multiple affinity states when both coupled to and uncoupled from G-proteins(s). These findings suggest that CGRP occupancy of its receptor induces conformational changes in the receptor that may be involved in its coupling to G-proteins and that the resulting ligand–receptor–G-protein ternary complex exists in multiple affinity conformational states. It seems likely that the multiple affinity states of the CGRP receptor ternary complex are involved differentially in signaling by and desensitization of the receptor. This evidence for agonist-induced conformational changes in a G-protein-coupled receptor prior to its coupling with G-protein(s) and for the existence of the ligand–receptor–G-protein ternary complex in multiple affinity conformational states is novel and extends our current understanding of the nature of the processes involved in agonist-dependent activation of G-protein-coupled receptors.Key words: calcitonin gene related peptide receptor, G-protein, multiple affinity.

Sign in / Sign up

Export Citation Format

Share Document