(A) Schematic illustrations of Aβ channels and β-barrels in lipid membranes. (B) Schematics of the CNpNC (left) and NCpCN (right) topologies of Aβ(17–42) channels. The Aβ monomers, which were taken from the NMR pentamer structure in the PDB databank (ID: 2BEG), exhibited the U-shaped strand-turn-strand conformation. Top panel: initial annular channel topologies shown as a cross-section of a hollowed cylinder in grey with a cut along the pore axis. The Aβ(17–42) peptide in ribbon representation was projected into the cross-section area. Middle panel: the topologies of Aβ peptides drawn by connected arrows. Bottom panel: ribbon representations of Aβ backbones. (C) Comparison between computed Aβ(17–42) channel structures and high-resolution AFM data. The simulated channel structures for (a) 16-mer, (b) 20-mer and (c) 24-mer showed four to five subunits, in agreement with the AFM images (d and e). (D) Aβ(9–42) channels (left) and β-barrels (right). Top panel: angle views of the pore structures, where pore structures were shown in ribbon representation. Bottom panel: lateral views of the pore structure, where the cross-sectioned pores were shown in surface representation with the degree of the pore diameter colored in the order of red < green < blue. Panels reproduced from Refs. 52, 54–55, 57–58. Copyrights 2014 The Royal Society of Chemistry, 2007 the Biophysical Society, 2010 American Chemical Society, 2010 National Academy of Sciences and 2010 Elsevier Ltd.