About the Authors
Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
The authors have declared that no conflicts of interest exist.
MS, DDW, NM, and EKO conceived and designed the experiments. MS, DDW, and NM performed the experiments. MS, DDW, and NM analyzed the data. MS, DDW, and EKO wrote the paper.