Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America.|Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America.|Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America.|Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America.