* Corresponding authors

^a Department of Bionanotechnology, Hanyang University, Ansan, Korea
E-mail: pchae@hanyang.ac.kr

^b Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305, USA
E-mail: kobilka@stanford.edu

^c Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
E-mail: cllo@sund.ku.dk

^d Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
E-mail: lan.guan@ttuhsc.edu

^e Department of Life Sciences, Imperial College London, London, SW7 2AZ UK
E-mail: b.byrne@imperial.ac.uk