Fig. 5.

Amyloidogenic core of SAA1 and amyloid formation. (A) Amyloid formation of SAA1 peptides using ThT binding assays. (B) EM images of fibrils formed by helix 1 (Upper) and 3 (Lower, and the fibrils are indicated by arrows) peptides. (C) Binding of ThT to hexameric (green, red) and trimeric (blue) SAA1.1 in the presence (green) and absence of cathepsin B. ThT alone is shown in black. (D) Binding of ThT to 70 µg/mL aggregated (black) or monomeric (red) MBP-SAA1₈₉, hexameric SAA1.1 (green), MBP (blue), and aggregated IgG₁ (pink). (E) EM image of negatively stained _his6SAA1 protein (Top) and the class averaging of _his6SAA1 particles (Middle). (Bottom) Surface rendering of the _his6SAA1 hexamer in two views, with each trimer colored in green and blue. (F) EM image of negatively stained MBP-SAA1₈₉ oligomers (Upper) and their class average (Lower). (G) Images of MBP-SAA1₈₉ aggregates showing repeating nods in either circular or linear assemblies. (Scale bars, 20 nm.)