Pauline Bennett1, Peter J Knight2, K W Ranatunga3. 1. Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK. pauline.bennett@kcl.ac.uk. 2. Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds, UK. 3. School of Physiology, Pharmacology & Neurosciences, University of Bristol, Bristol, UK.