Appendix A  Supplementary data
Supplementary materials

Acknowledgements
We thank Victoria McParland for preparing the first samples of β2m amyloid suitable for study; Louise Serpell and the Radford group for helpful discussions; Luchun Wang for EM support; David Houldershaw and Richard Westlake for computing support; Andreas Engel for providing STEM facilities; Françoise Erne-Brand and Philippe Ringler for STEM experiments; and the Wellcome Trust (069064/Z/02/A), the Biotechnology and Biological Sciences Research Council (27/B18659), and European Union 3DEM Network of Excellence (LSHG-CT-2004-502828) for funding. The STEM work was supported by the Swiss National Foundation (SNF grant 3100A0-108299). Appendix A  Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.jmb.2009.03.066.
Cryo EM maps are deposited in the EM database (EMDB 1613 and 1614).