1 Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA, and Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
2 Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA, and Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA. [email protected].