1. Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
2. Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
3. Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
4. National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA 92093, USA
5. Department of Cellular and Molecular Medicine, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
6. Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
7. Department of Cell Biology, Johns Hopkins University, Baltimore, MD, USA