1. University of Wisconsin Department of Biochemistry, , Madison, WI, USA
2. Cryo-Electron Microscopy Research Center , Department of Biochemistry, , Madison, WI, USA
3. University of Wisconsin , Department of Biochemistry, , Madison, WI, USA
4. Midwest Center for Cryo-Electron Tomography , Department of Biochemistry, , Madison, WI, USA
5. Morgridge Institute for Research , Madison, WI, USA