1. State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.
2. Center for Structural Biology, School of Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China.
3. Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
4. National Institute of Biological Sciences, Beijing 102206, China.
5. Molecular Design and Chemical Biology, Therapeutic Modalities, Roche Pharma Research and Early Development, Roche Innovation Center Shanghai, Shanghai 201203, China.
6. Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA.