Role of the Cys18–Cys274 disulfide bond and of the third extracellular loop in the constitutive activation and internalization of angiotensin II type 1 receptor

Correa, Silvana Aparecida Alves; Pignatari, Graciela Conceição; Ferro, Emer S.; Pacheco, Nelson A.S.; Costa-Neto, Cláudio M.; Pesquero, João Bosco; Oliveira, Laerte; Paiva, Antonio C. M.; Shimuta, Suma I.

doi:10.1016/j.regpep.2006.02.008

Cited by 18 publications

(14 citation statements)

References 36 publications

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“…The corresponding segment is found in the ECL3/TMVII region in the CXCR4 X‐ray structure as well as in derived ApelinR and AT1 homology models (45). Interestingly, the Cys residue of the motif establishes a disulfide bond with a Cys residue located at the N terminus tail of the CXCR4 and AT1, and it has been shown to be crucial for SDF‐1α and AngII binding by limiting the conformational freedom of the ECL3/TMVII interface (34, 46, 47). This disulfide bridge is not seen in the ApelinR models derived from the CCK1R and β2AR templates, suggesting that the conservation of such disulfide bridge in the γ subfamily of GPCR may probably account for the relevance of the CXCR4 crystallographic structure as template for GPCR homology models from this branch.…”

Section: Discussionmentioning

confidence: 99%

New structural insights into the apelin receptor: identification of key residues for apelin binding

et al. 2014

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Apelin is the endogenous ligand of the orphan 7-transmembrane domain GPCR APJ, now named the apelin receptor (ApelinR). Apelin plays a prominent role in body fluid and cardiovascular homeostasis. To better understand the structural organization of the ApelinR, we built 3 homology 3-dimensional (3D) models of the human ApelinR using the validated cholecystokinin receptor-1 3D model or the X-ray structures of the β2-adrenergic and CXCR4 receptors as templates. Docking of the pyroglutamyl form of apelin 13 (pE13F) into these models revealed the conservation at the bottom of the binding site of a hydrophobic cavity in which the C-terminal Phe of pE13F was embedded. In contrast, at the top of the binding site, depending on the model, different interactions were visualized between acidic residues of the ApelinR and the basic residues of pE13F. Using site-directed mutagenesis, we showed that Asp 92, Glu 172, and Asp 282 of rat ApelinR are key residues in apelin binding by interacting with Lys 8, Arg 2, and Arg 4 of pE13F, respectively. These residues are only seen in the CXCR4-based ApelinR 3D model, further validating this model. These findings bring new insights into the structural organization of the ApelinR and the mode of apelin binding.

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Section: Discussionmentioning

confidence: 99%

New structural insights into the apelin receptor: identification of key residues for apelin binding

et al. 2014

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“…Consistent with this view obtained directly from x-ray crystallography, our homology model also showed a highly ordered hairpin-like conformation stabilized by a network of intramolecular interactions. The stability and integrity of ECL2 have been shown to affect ligand binding and receptor activation in many GPCRs by altering the molecular shape and size of the entrance of ligand-binding site (14,(45)(46)(47)(48)(49)(50)(51)(52)(53)(54). Interestingly, disrupting the disulfide bond between Cys-118 and Cys-195 significantly enhanced -TIA affinity ϳ60-fold, had no effect on prazosin affinity, and reduced NE potency ϳ300-fold.…”

Section: Discussionmentioning

confidence: 99%

Conopeptide ρ-TIA Defines a New Allosteric Site on the Extracellular Surface of the α1B-Adrenoceptor

Ragnarsson

Wang

Andersson

et al. 2013

Journal of Biological Chemistry

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Background: Mechanistic insight into allosteric modulation of GPCRs can facilitate antagonist design. Results: Extracellular surface residues (ECS) of the ␣ 1B -adrenoceptor at the base of extracellular loop 3 interact with the allosteric antagonist TIA. Conclusion:The identified ECS pharmacophore provides the first structural constraints for allosteric antagonist design at ␣ 1 -adrenoceptors. Significance: Binding to the ECS of a GPCR can allosterically inhibit agonist signaling.

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“…For other disulfide bonds, the observed effects can be more receptor specific. For example, breaking the N‐terminus‐ECL3 disulfide bond decreased agonist affinity in the CXCR4 (Zhou and Tai, 2000) but engendered constitutive activity on the angiotensin II type 1 receptor (AT 1 R; Correa et al ., 2006). Likewise, breaking the N‐terminus‐ECL2 disulfide in GPR39 increased agonist (Zn 2+ ) potency (Storjohann et al ., 2008).…”

Section: Family a Gpcrs: Ecl Structural Aspectsmentioning

confidence: 99%

Lifting the lid on GPCRs: the role of extracellular loops

Wheatley

Wootten

Conner

et al. 2012

British J Pharmacology

261

256

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GPCRs exhibit a common architecture of seven transmembrane helices (TMs) linked by intracellular loops and extracellular loops (ECLs). Given their peripheral location to the site of G-protein interaction, it might be assumed that ECL segments merely link the important TMs within the helical bundle of the receptor. However, compelling evidence has emerged in recent years revealing a critical role for ECLs in many fundamental aspects of GPCR function, which supported by recent GPCR crystal structures has provided mechanistic insights. This review will present current understanding of the key roles of ECLs in ligand binding, activation and regulation of both family A and family B GPCRs. LINKED ARTICLESThis article is part of a themed section on the Molecular Pharmacology of G Protein-Coupled Receptors (GPCRs). To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-6. To view the 2010 themed section on the same topic visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2010.159.issue-5/issuetoc Abbreviations A2AR, A2A adenosine receptor; AT1R, angiotensin II type 1 receptor; b1AR, b1-adrenergic receptor; b2AR, b2-adrenergic receptor; C5aR, complement factor 5a receptor; CAM, constitutively activating mutation; CGRP, calcitonin gene-related peptide; CLR, calcitonin receptor-like receptor; CRF, corticotropin-releasing factor; D3R (D2R), D3 (D2) dopamine receptor; GLP-1, glucagon-like peptide-1; ECL, extracellular loop; H1R, histamine H1 receptor; HIV-1, human immunodeficiency virus type 1; M2R (M4R), M2 (M4) muscarinic acetylcholine receptor; NDI, nephrogenic diabetes insipidus; PACAP, pituitary adenylyl cyclase-activating peptide; PTH, parathyroid hormone; TM, transmembrane helix; V1aR, V1a vasopressin receptor; V2R, V2 vasopressin receptor IntroductionGPCRs form the largest class of membrane proteins in the human genome, with >800 unique receptors. They are central to cell signalling and are of great commercial value to the pharmaceutical industry worldwide, with~50% of clinically marketed drugs and~25% of top-selling drugs targeting this receptor family (Lagerström and Schiöth, 2008). GPCRs are activated by a wide variety of agonists which differ with respect to chemical class, physical properties and size -from photons and small biogenic amines to peptides and large glycoproteins (Hill, 2006).Historically, it was envisaged that binding any agonist induced the 'on' conformation that activated a single G-protein type to initiate an intracellular signal. It is now recognized that GPCR signalling is much more complex than this. Individual GPCRs can activate multiple types of G-protein, not just one type, and signalling can be G-protein independent, such as b-arrestin-dependent GPCR activation of MAPK (Azzi et al., 2003). Furthermore, there is compelling evidence to indicate that the classification of an individual ligand can be dictated by the signalling system being observed. For example, the peptide ligand SP-G is an antagonist for V 1a vasopressin receptor (V1aR) inositol phos...

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Role of the Cys18–Cys274 disulfide bond and of the third extracellular loop in the constitutive activation and internalization of angiotensin II type 1 receptor

Cited by 18 publications

References 36 publications

New structural insights into the apelin receptor: identification of key residues for apelin binding

New structural insights into the apelin receptor: identification of key residues for apelin binding

Conopeptide ρ-TIA Defines a New Allosteric Site on the Extracellular Surface of the α1B-Adrenoceptor

Lifting the lid on GPCRs: the role of extracellular loops

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