[1] Univ Dundee, Sch Life Sci, Dundee DD1 5EH, Scotland
[2] Univ Leeds, Sch Biochem & Mol Biol, Leeds LS2 9JT, W Yorkshire, England
[3] Univ Geneva, Dept Morphol, CMU, CH-1211 Geneva, Switzerland
[4] Inst Mol & Cell Biol, Membrane Biol Lab, Singapore 117609, Singapore