1. Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
2. Campus Mass Spectrometry Facilities, University of California, Davis, Davis, California, USA
3. Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, USA
4. Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York, USA
5. Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
6. Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, USA