[1] Univ Calif San Francisco, Howard Hughes Med Inst, San Francisco, CA 94158 USA
[2] Univ Calif San Francisco, Dept Mol & Cellular Pharmacol, San Francisco, CA 94158 USA
[3] Univ Calif Davis, Dept Mol & Cellular Biol, Davis, CA 95616 USA
[4] Marine Biol Lab, Physiol Course, Woods Hole, MA 02543 USA