Mapping the CGRP receptor ligand binding domain: Tryptophan-84 of RAMP1 is critical for agonist and antagonist binding

The calcitonin receptor-like receptor (CLR) associates with the accessory protein RAMP1 to form a receptor for the neuropeptide calcitonin gene-related peptide (CGRP). Multiple lines of evidence have implicated CGRP in the pathophysiology of migraine headache making the CGRP receptor an attractive t...

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Bibliographic Details
Published in:	Biochemical and biophysical research communications Vol. 394; no. 1; pp. 141 - 145
Main Authors:	Moore, E.L., Gingell, J.J., Kane, S.A., Hay, D.L., Salvatore, C.A.
Format:	Journal Article
Language:	English
Published:	United States Elsevier Inc 26-03-2010
Subjects:	Azepines - chemistry Azepines - metabolism Azepines - pharmacology Calcitonin Gene-Related Peptide Receptor Antagonists Calcitonin Receptor-Like Protein CGRP Crystallography, X-Ray Dipeptides - chemistry Dipeptides - metabolism Dipeptides - pharmacology GPCR Humans Imidazoles - chemistry Imidazoles - metabolism Imidazoles - pharmacology Intracellular Signaling Peptides and Proteins - chemistry Intracellular Signaling Peptides and Proteins - genetics Intracellular Signaling Peptides and Proteins - metabolism Ligands Membrane Proteins - chemistry Membrane Proteins - genetics Membrane Proteins - metabolism Migraine Migraine Disorders - metabolism Piperazines - chemistry Piperazines - metabolism Piperazines - pharmacology Protein Interaction Domains and Motifs Protein Interaction Mapping Quinazolines - chemistry Quinazolines - metabolism Quinazolines - pharmacology Receptor Activity-Modifying Protein 1 Receptor Activity-Modifying Proteins Receptors, Calcitonin - metabolism Receptors, Calcitonin Gene-Related Peptide - agonists Receptors, Calcitonin Gene-Related Peptide - metabolism Telcagepant Tryptophan - metabolism GPCR Telcagepant CGRP Migraine
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Summary:	The calcitonin receptor-like receptor (CLR) associates with the accessory protein RAMP1 to form a receptor for the neuropeptide calcitonin gene-related peptide (CGRP). Multiple lines of evidence have implicated CGRP in the pathophysiology of migraine headache making the CGRP receptor an attractive target for development of small-molecule antagonists as a novel treatment for this debilitating condition. The CGRP receptor antagonists telcagepant and olcegepant (BIBN4096BS) have demonstrated clinical efficacy in the treatment of migraine and there is now a need to better understand how these molecules interact with the receptor. Previous work has shown the extracellular portion of RAMP1 to be important for binding of these antagonists, with tryptophan-74 being a key interaction site. The crystal structure of the extracellular portion of human RAMP1 placed tryptophan-74 in a hydrophobic patch hypothesized to interact with CGRP receptor ligands and also identified nearby residues that may be important for ligand binding. In this study we explored the role played by these residues of RAMP1 using an alanine replacement strategy. We confirmed a role for tryptophan-74 in antagonist binding and also identified arginine-67 as being important for binding of telcagepant but not compound 3, a close analog of BIBN4096BS. We also identified tryptophan-84 as being critical for both high-affinity binding of the non-peptide antagonists as well as the peptides CGRP and CGRP(8–37). These data for the first time pinpoint a specific RAMP1 residue important for both antagonist and agonist potency and are consistent with the N-terminal domain of RAMP1 forming the binding pocket interface with CLR.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0006-291X 1090-2104
DOI:	10.1016/j.bbrc.2010.02.131