The role of the extracellular loops of the CGRP receptor, a family B GPCR

2012 ◽  
Vol 40 (2) ◽  
pp. 433-437 ◽  
Author(s):  
James Barwell ◽  
Michael J. Woolley ◽  
Mark Wheatley ◽  
Alex C. Conner ◽  
David R. Poyner
Keyword(s):  
Surface Expression ◽  
Receptor Activation ◽  
Receptor Expression ◽  
Cell Surface Expression ◽  
Calcitonin Receptor ◽  
Transmembrane Helices ◽  
Extracellular Loops ◽  
Calcitonin Gene ◽  
G Protein Coupled

The CGRP (calcitonin gene-related peptide) receptor is a family B GPCR (G-protein-coupled receptor). It consists of a GPCR, CLR (calcitonin receptor-like receptor) and an accessory protein, RAMP1 (receptor activity-modifying protein 1). RAMP1 is needed for CGRP binding and also cell-surface expression of CLR. There have been few systematic studies of the ECLs (extracellular loops) of family B GPCRs. However, they are likely to be especially important for the interaction of the N-termini of the peptide agonists that are the natural agonists for these receptors. We have carried out alanine scans on all three ECLs of CLR, as well as their associated juxtamembrane regions. Residues within all three loops influence CGRP binding and receptor activation. Mutation of Ala203 and Ala206 on ECL1 to leucine increased the affinity of CGRP. Residues at the top of TM (transmembrane) helices 2 and 3 influenced CGRP binding and receptor activation. L351A and E357A in TM6/ECL3 reduced receptor expression and may be needed for CLR association with RAMP1. ECL2 seems especially important for CLR function; of the 16 residues so far examined in this loop, eight residues reduce the potency of CGRP at stimulating cAMP production when mutated to alanine.

The activation of the CGRP receptor

2013 ◽  
Vol 41 (1) ◽  
pp. 180-184 ◽  
Author(s):  
James Barwell ◽  
Mark Wheatley ◽  
Alex C. Conner ◽  
Bruck Taddese ◽  
Shabana Vohra ◽  
...  
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Accessory Protein ◽  
Calcitonin Receptor ◽  
Cgrp Receptor ◽  
Peptide Receptor ◽  
Calcitonin Gene ◽  
New Knowledge ◽  
G Protein Coupled

The CGRP (calcitonin gene-related peptide) receptor is a family B GPCR (G-protein-coupled receptor). It consists of a GPCR, CLR (calcitonin receptor-like receptor) and an accessory protein, RAMP1 (receptor activity modifying protein 1). RAMP1 is needed for CGRP binding and also cell-surface expression of CLR. CLR is an example of a family B GPCR. Unlike family A GPCRs, little is known about how these receptors are activated by their endogenous ligands. This review considers what is known about the activation of family B GPCRs and then considers how this might be applied to CLR, particularly in light of new knowledge of the crystal structures of family A GPCRs.

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 Structural determinants regulating cell surface targeting of melanocortin receptors

2013 ◽  
Vol 51 (2) ◽  
pp. R23-R32 ◽  
Author(s):  
A R Rodrigues ◽  
D Sousa ◽  
H Almeida ◽  
A M Gouveia
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Melanocortin Receptors ◽  
Control Mechanisms ◽  
Structural Determinants ◽  
Surface Integration ◽  
C Terminus ◽  
G Protein Coupled

Melanocortin receptors (MCRs) belong to the G-protein-coupled receptor family of transmembrane proteins. They recognize specific ligands named melanocortins that are mainly produced in the pituitary and hypothalamus. Newly synthesized MCRs at the endoplasmic reticulum are subjected to quality control mechanisms that screen for the correct structure, folding or processing, essential for their proper cell surface expression. Some motifs, located at the N- or C-terminus or even on transmembrane and in loop regions, have been implicated in these biological processes. This article reviews these specific domains and the role of accessory proteins and post-translation modifications in MCRs' targeting to cell surface. Additionally, promising approaches involving pharmacological stabilization of misfolded and misrouted mutant MCRs, which improve their forward transport, are reported. Understanding the MCRs' structural determinants fundamental for their proper cell surface integration is essential for correcting abnormalities found in some diseases.

Interaction of calcitonin-gene-related peptide with its receptors

2002 ◽  
Vol 30 (4) ◽  
pp. 451-455 ◽  
Author(s):  
A. C. Conner ◽  
D. L. Hay ◽  
S. G. Howitt ◽  
K. Kilk ◽  
Ü. Langel ◽  
...  
Keyword(s):  
Direct Contact ◽  
Transmembrane Domain ◽  
Receptor Activation ◽  
Calcitonin Gene Related Peptide ◽  
Type Ii ◽  
Calcitonin Receptor ◽  
High Affinity ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
G Protein Coupled

The receptor for calcitonin-gene-related peptide (CGRP) is a heterodimer formed by calcitonin-receptor-like receptor (CRLR), a type II (family B) G-protein-coupled receptor, and receptor-activity-modifying protein 1 (RAMP1), a single-membrane-pass protein. It is likely that the first seven or so amino acids of CGRP (which form a disulphide-bonded loop) interact with the transmembrane domain of CRLR to cause receptor activation. The rest of the CGRP molecule falls into three domains. Residues 28–37 and 8–18 are normally required for high-affinity binding, while residues 19–27 form a hinge region. The 28–37 region is almost certainly in direct contact with the receptor; 8–18 may make additional receptor contacts or may stabilize an appropriate conformation of 28–37. It is likely that these regions of CGRP interact both with CRLR and with the extracellular domain of RAMP1.

scholarly journals Repulsive Separation of the Cytoplasmic Ends of Transmembrane Helices 3 and 6 Is Linked to Receptor Activation in a Novel Thyrotropin Receptor Mutant (M626I)

2006 ◽  
Vol 20 (4) ◽  
pp. 893-903 ◽  
Author(s):  
Usanee Ringkananont ◽  
Joost Van Durme ◽  
Lucia Montanelli ◽  
Figen Ugrasbul ◽  
Y. Miles Yu ◽  
...  
Keyword(s):  
G Protein ◽  
Surface Expression ◽  
Receptor Activation ◽  
Cell Surface Expression ◽  
Constitutive Activity ◽  
Transmembrane Helices ◽  
Wild Type ◽  
Gpcr Activation ◽  
Camp Generation ◽  
Site Directed Spin Labeling

Abstract Ligand-dependent activation of G protein-coupled receptors (GPCRs) involves repositioning of the juxtacytoplasmic ends of transmembrane helices TM3 and TM6. This concept, inferred from site-directed spin labeling studies, is supported by chemical cross-linking of the cytoplasmic ends of TM3 and TM6 blocking GPCR activation. Here we report a novel constitutive active mutation (M626I) in TM6 of the TSH receptor (TSHR), identified in affected members of a family with nonautoimmune hyperthyroidism. The specific constitutive activity of M626I, measured by its basal cAMP generation corrected for cell surface expression, was 13-fold higher than that of wild-type TSHR. Homology modeling of the TSHR serpentine domain based on the rhodopsin crystal structure suggests that M626 faces the side chain of I515 of TM3 near the membrane-cytoplasmic junction. Steric hindrance of the introduced isoleucine by I515 is consistent with the fact that shorter or more flexible side chains at position 626 did not increase constitutivity. Furthermore, a reciprocal mutation at position 515 (I515M), when introduced into the M626I background, acts as revertant mutation by allowing accommodation of the isoleucine sidechain at position 626 and fully restoring the constitutive activity to the level of wild-type TSHR. Thus, repulsive separation of the juxtacytoplasmic TM6 and TM3 in the M626I model conclusively demonstrates a direct link between the opening of this cytoplasmic face of the receptor structure and G protein coupling.

scholarly journals Analysis of the Role of N-Linked Glycosylation in Cell Surface Expression, Function, and Binding Properties of SARS-CoV-2 Receptor ACE2

2021 ◽  
Author(s):  
Raymond Rowland ◽  
Alberto Brandariz-Nuñez
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Receptor Interaction ◽  
Minimal Effect ◽  
Binding Properties ◽  
Virus Receptor

Understanding the role of glycosylation in the virus-receptor interaction is important for developing approaches that disrupt infection. In this study, we showed that deglycosylation of both ACE2 and S had a minimal effect on the spike-ACE2 interaction.

scholarly journals Exploring Ligand Binding to Calcitonin Gene-Related Peptide Receptors

2021 ◽  
Vol 8 ◽  
Author(s):  
Giuseppe Deganutti ◽  
Silvia Atanasio ◽  
Roxana-Maria Rujan ◽  
Patrick M. Sexton ◽  
Denise Wootten ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ligand Binding ◽  
Calcitonin Gene Related Peptide ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
Approved Drugs ◽  
G Protein Coupled ◽  
Dynamic Docking ◽  
Receptor Family

Class B1 G protein-coupled receptors (GPCRs) are important targets for many diseases, including cancer, diabetes, and heart disease. All the approved drugs for this receptor family are peptides that mimic the endogenous activating hormones. An understanding of how agonists bind and activate class B1 GPCRs is fundamental for the development of therapeutic small molecules. We combined supervised molecular dynamics (SuMD) and classic molecular dynamics (cMD) simulations to study the binding of the calcitonin gene-related peptide (CGRP) to the CGRP receptor (CGRPR). We also evaluated the association and dissociation of the antagonist telcagepant from the extracellular domain (ECD) of CGRPR and the water network perturbation upon binding. This study, which represents the first example of dynamic docking of a class B1 GPCR peptide, delivers insights on several aspects of ligand binding to CGRPR, expanding understanding of the role of the ECD and the receptor-activity modifying protein 1 (RAMP1) on agonist selectivity.

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