1. Institute for Molecular Biosciences and
2. Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia;
3. Garvan Institute of Medical Research, St. Vincent's Hospital, Darlinghurst, 2010 New South Wales, Australia; and
4. Membrane Biology Laboratory, Institute of Molecular and Cell Biology, National University of Singapore, Singapore 117609