1. Materials, Physics, and Molecular, Cellular, and Developmental Biology Departments, University of California, Santa Barbara, Santa Barbara, California 93106, United States
2. State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
3. The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, New York 10027, United States
4. Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States