Abstract
G-protein-coupled receptors (GPCRs) are the largest superfamily of transmembrane proteins and the targets of over 30% of currently marketed pharmaceuticals. Although several structures have been solved for GPCR-G protein complexes, few are in a lipid membrane environment. Here, we report cryo-EM structures of complexes of neurotensin, neurotensin receptor 1 and Gαi1β1γ1 in two conformational states, resolved to resolutions of 4.1 and 4.2 Å. The structures, determined in a lipid bilayer without any stabilizing antibodies or nanobodies, reveal an extended network of protein-protein interactions at the GPCR-G protein interface as compared to structures obtained in detergent micelles. The findings show that the lipid membrane modulates the structure and dynamics of complex formation and provide a molecular explanation for the stronger interaction between GPCRs and G proteins in lipid bilayers. We propose an allosteric mechanism for GDP release, providing new insights into the activation of G proteins for downstream signaling.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Allosteric Regulation
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Cryoelectron Microscopy*
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GTP-Binding Protein alpha Subunits, Gi-Go / chemistry
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GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
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GTP-Binding Protein alpha Subunits, Gi-Go / ultrastructure
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GTP-Binding Protein beta Subunits / chemistry
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GTP-Binding Protein beta Subunits / metabolism
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GTP-Binding Protein beta Subunits / ultrastructure
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GTP-Binding Protein gamma Subunits / chemistry
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GTP-Binding Protein gamma Subunits / metabolism
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GTP-Binding Protein gamma Subunits / ultrastructure
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Guanosine Diphosphate / metabolism
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Heterotrimeric GTP-Binding Proteins / chemistry
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Heterotrimeric GTP-Binding Proteins / metabolism*
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Heterotrimeric GTP-Binding Proteins / ultrastructure*
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Humans
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Lipid Bilayers* / chemistry
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Lipid Bilayers* / metabolism
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Micelles
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Models, Molecular
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Nanostructures / chemistry*
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Neurotensin / chemistry
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Neurotensin / metabolism
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Protein Conformation
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Receptors, Neurotensin / chemistry
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Receptors, Neurotensin / metabolism*
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Receptors, Neurotensin / ultrastructure*
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Signal Transduction
Substances
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GTP-Binding Protein beta Subunits
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GTP-Binding Protein gamma Subunits
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Lipid Bilayers
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Micelles
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Receptors, Neurotensin
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neurotensin type 1 receptor
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Guanosine Diphosphate
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Neurotensin
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GTP-Binding Protein alpha Subunits, Gi-Go
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Heterotrimeric GTP-Binding Proteins