1. Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse–Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
2. Faculty of Medicine, Libin Institute, Calgary T2N 4N1, Canada
3. Laboratory for Membrane Protein Dynamics, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark