1. Department of Molecular Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G0A4, Canada
2. Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Cantoblanco, 28049 Madrid, Spain
3. Electron Microscopy Unit UCCT/ISCIII, 28220 Majadahonda, Spain
4. School of Biomedical Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
5. Electron Microscope Unit, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW 2052, Australia