Figure 1.

Cartoon representations of cross-β structural motifs. (a,b) Parallel and antiparallel cross-β motifs, as would occur in amyloid fibrils formed by short peptides with a single β-strand segment. The fibrils might contain multiple copies of the same motif, stacked against one another in a direction perpendicular to the growth direction and to the β-strand direction. (c,d) Double-layered parallel and antiparallel cross-β motifs, as would occur in amyloid fibrils formed by longer peptides with two β-strand segments. Again, the fibrils might contain multiple copies of the same motif.