Fig. 3. Lumpy Q51 filaments exhibit a large range of widths.

a Schematic of the Q51 construct, lacking all mEx1 domains except for the polyQ tract. b Slice parallel to the xy plane (~2.1 nm thick) through a representative 4x downsampled cryoET tomogram of aggregated Q51 reconstructed with compressed sensing and corresponding 3D annotation. Zoomed-in views of xy slices (~0.5 nm thick) from selected regions of the tomogram shown in “a” but without any downsampling, exhibiting c a pseudo-periodic pattern of repeating lumps along the length of a Q51 filament (blue arrows), and d regions in thin filaments that are as thin as ~2 nm in width (red arrows). e Examples of 2D xy slices through representative 3D subtomograms of Q51 filament segments showing a wide variation in width, including super-thin regions ~2 nm in width (red arrows). Scale bars: 100 nm (b), 15 nm (c, d), and 17 nm (e).