Conformational dynamics of a G protein–coupled receptor helix 8 in lipid membranes

Juan C. Muñoz-García, Patricia M. Dijkman, Steven Lavington, Patricia Suemy Kumagai, Rosana Inacio dos Reis, Daniel Yin, Phillip J. Stansfeld, Antonio José Costa-Filho, Anthony Watts

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Abstract

G protein–coupled receptors (GPCRs) are the largest and pharmaceutically most important class of membrane proteins encoded in the human genome, characterized by a seven-transmembrane helix architecture and a C-terminal amphipathic helix 8 (H8). In a minority of GPCR structures solved to date, H8 either is absent or adopts an unusual conformation. The controversial existence of H8 of the class A GPCR neurotensin receptor 1 (NTS1) has been examined here for the nonthermostabilized receptor in a functionally supporting membrane environment using electron paramagnetic resonance, molecular dynamics simulations, and circular dichroism. Lipid-protein interactions with phosphatidylserine and phosphatidylethanolamine lipids, in particular, stabilize the residues 374 to 390 of NTS1 into forming a helix. Furthermore, introduction of a helix-breaking proline residue in H8 elicited an increase in ß-arrestin–NTS1 interactions observed in pull-down assays, suggesting that the structure and/or dynamics of H8 might play an important role in GPCR signaling.
Original languageEnglish
Article numbereaav8207
JournalScience Advances
Volume6
Issue number33
DOIs
Publication statusPublished - 14 Aug 2020

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