About the Authors
Department of Biochemistry, School of Medicine, University of Washington, Seattle, Washington, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: LTG AMW. Performed the experiments: LTG KKF TP. Analyzed the data: LTG. Contributed reagents/materials/analysis tools: LTG TP. Wrote the paper: LTG AMW.