Essential role for the second extracellular loop in c5a receptor activation

ABSTRACT More than 90% of G protein–coupled receptors (GPCRs) contain a disulfide bridge that tethers the second extracellular loop (EC2) to the third transmembrane helix. To determine the

importance of EC2 and its disulfide bridge in receptor activation, we subjected this region of the complement factor 5a receptor (C5aR) to random saturation mutagenesis and screened for

functional receptors in yeast. The cysteine forming the disulfide bridge was the only conserved residue in the EC2-mutated receptors. Notably, ∼80% of the functional receptors exhibited

potent constitutive activity. These results demonstrate an unexpected role for EC2 as a negative regulator of C5a receptor activation. We propose that in other GPCRs, EC2 might serve a

similar role by stabilizing the inactive state of the receptor. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution ACCESS

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institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS MECHANISM OF ACTIVATION AND BIASED SIGNALING IN COMPLEMENT RECEPTOR C5AR1

Article Open access 17 February 2023 SUBMOLECULAR PROBING OF THE COMPLEMENT C5A RECEPTOR–LIGAND BINDING REVEALS A COOPERATIVE TWO-SITE BINDING MECHANISM Article Open access 18 December 2020

ACTIVATION MECHANISM OF THE CLASS D FUNGAL GPCR DIMER STE2 Article Open access 16 March 2022 ACCESSION CODES ACCESSIONS GENBANK/EMBL/DDBJ * AAF13030 * AAG12474 * AAG12475 * O70129 * P21730 *

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Download references ACKNOWLEDGEMENTS We thank G. Nikiforovich, H. Bourne, K. Blumer, E. Meng and members of the Baranski lab for helpful discussions and review of the manuscript. This work

was supported by an award from the American Heart Association (J.M.K.) and by grants from the American Cancer Society IRG-58-010-43 (T.J.B.), the Culpeper Award, Rockefeller Brothers Fund

(T.J.B.), and the US National Institutes of Health, GM63720-01 (T.J.B.). AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Departments of Medicine and Molecular Biology and Pharmacology,

Washington University School of Medicine, Campus Box 8127, 660 S. Euclid Avenue, St. Louis, 63110, Missouri, USA Jeffery M Klco, Christina B Wiegand, Kirk Narzinski & Thomas J Baranski

Authors * Jeffery M Klco View author publications You can also search for this author inPubMed Google Scholar * Christina B Wiegand View author publications You can also search for this

author inPubMed Google Scholar * Kirk Narzinski View author publications You can also search for this author inPubMed Google Scholar * Thomas J Baranski View author publications You can also

search for this author inPubMed Google Scholar CORRESPONDING AUTHOR Correspondence to Thomas J Baranski. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing financial

interests. SUPPLEMENTARY INFORMATION SUPPLEMENTARY FIG. 1 Localization of C5aR cysteine mutants in yeast. (PDF 851 kb) SUPPLEMENTARY FIG. 2 Expression of NQ receptors in yeast. (PDF 367 kb)

SUPPLEMENTARY FIG. 3 Alignment of EC2 residues in C5aR and rhodopsin. (PDF 42 kb) RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Klco, J., Wiegand, C.,

Narzinski, K. _et al._ Essential role for the second extracellular loop in C5a receptor activation. _Nat Struct Mol Biol_ 12, 320–326 (2005). https://doi.org/10.1038/nsmb913 Download

citation * Received: 27 October 2004 * Accepted: 07 February 2005 * Published: 13 March 2005 * Issue Date: 01 April 2005 * DOI: https://doi.org/10.1038/nsmb913 SHARE THIS ARTICLE Anyone you

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