1. Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, Merced, California, USA
2. Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, USA
3. Tetrad Program, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, USA
4. Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, USA