Figure 6. Model of an Aβ42 octamer. Features and colors are like those of Fig. 3. (a) Flattened schematic of four subunits of the outer and inner β-barrels. (b & c) Ribbon representation of the octamer backbone as viewed from the side through a perpendicular 2-fold axis between yellow S2 strands and from the top. (d-f) Cross-sections with side chains colored by element of the top region, the next region down, and the middle region.