The G‐Protein‐Coupled Neuropeptide Y Receptor Type 2 is Highly Dynamic in Lipid Membranes as Revealed by Solid‐State NMR Spectroscopy |
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| Authors: | Dr Peter Schmidt Dr Lars Thomas Paul Müller Dr Holger A Scheidt Prof?Dr Daniel Huster |
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| Affiliation: | 1. Institute of Medical Physics and Biophysics, University of Leipzig, H?rtelstrasse 16–18, 04107 Leipzig (Germany);2. Department of Chemical Sciences, TATA Institute of Fundamental Research, Homi Bhaba Road, Mumbai, 400 005 (India) |
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| Abstract: | In spite of the recent success in crystallizing several G‐protein‐coupled receptors (GPCRs), a comprehensive biophysical characterization of these molecules under physiological conditions also requires the study of the molecular dynamics of these proteins. The molecular mobility of the human neuropeptide Y receptor type 2 reconstituted into dimyristoylphosphatidylcholine (DMPC) membranes was investigated by means of solid‐state NMR spectroscopy. Static 15N NMR spectra show that the receptor performs axially symmetric motions in the membrane, and several residues undergo large amplitude fluctuations. This was confirmed by quantitative measurements of the motional 1H,13C order parameter of the CH, CH2, and CH3 groups. In directly polarized 13C NMR experiments, these order parameters showed astonishingly low values of SCH=0.55, S =0.33, and S =0.17, which corresponds to segmental amplitudes of approximately 50° in the backbone and approximately 50–60° in the side chain. At physiological temperature, 2H NMR spectra of the deuterated receptor showed a narrow component that is indicative of molecular order parameters of S≤0.3 superimposed with a very broad spectrum that could stem from the transmembrane α‐helices. These results suggest that the crystal structures of GPCRs only represent a static snapshot of these highly mobile molecules, which undergo significant structural fluctuations with relatively large amplitudes in a liquid‐crystalline membrane at physiological temperature. |
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| Keywords: | membranes NMR spectroscopy peptides proteins receptors |
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