1. Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, Texas 77030, United States
2. Center for Drug Discovery, Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas 77030, United States
3. Berkeley Center for Structural Biology, Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720, United States