1. Department of Cell Biology and Imaging Unit, Institute of Ophthalmology, University College London, London EC1V 9EL, England, UK
2. Crystallography, Institute for Structural and Molecular Biology, Birkbeck, University of London, London WC1E 7HX, England, UK
3. Nikon Imaging Centre, King’s College London, London SE1 1UL, England, UK