FIGURE 4.
Ultrastructure of spontaneously formed fibrils generated under acidic or chaotropic conditions. A, fibrils were analyzed by transmission electron microscopy using methylamine tungstate as a negative stain. No fibrils were visible using WT rPrP and acidic conditions. B and C, highly organized, linear fibrils are visible using K4A (B) and K4N (C) rPrP to form fibrils in acidic buffer conditions. D–F, WT (D), K4A (E), and K4N (F) all formed fibrils characterized by repeating twists and lateral bundling under chaotropic buffer conditions. Scale bar, 100 nm.