Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.|Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.