About the Authors

Karen S. Kim Guisbert

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

Hao Li

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

Christine Guthrie

To whom correspondence should be addressed. E-mail: guthrie@biochem.ucsf.edu

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

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

KSKG conceived and designed the experiments. KSKG performed the experiments. KSKG and CG analyzed the data. HL contributed reagents/materials/analysis tools. CG supervised all research. KSKG wrote the paper.