1. Department of Molecular and Cell Biology, Department of Physics, Biophysics Graduate Group, and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
2. Program in Systems Biology and Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605, USA
3. Department of Applied Physics, California Institute of Technology and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA