Extended Data Fig. 6: Putative NEC coat on negatively curved surfaces.

a, b, c, Slices through the same nucleoplasmic reticulum at different depths showing the distribution of the putative NEC layer. d, e, An enlarged section of panel c, showing top views of ring-like structures (highlighted in blue in e). f Overlay of the surface representation of the average volume of 121 ring-like particles from two tomograms and the spherical NEC lattice. Each ring could plausibly accommodate two concentric layers of pUL31/34 dimers. Averaging a more exhaustive (but less stringently picked) set of negatively curved lattice particles did not converge (and is therefore not shown), suggesting a high degree of variability. Notably, the membrane was not included as an alignment feature. g, The thickness and distance to the membrane of this layer are consistent with the spherical NEC lattice. Sections through the ring average volume with different C symmetries applied. Visually, C7 is the best match to C1 but it is possible these structures have no strict symmetry, as suggested by d, e. Note that symmetrisation in this case means addition of subvolumes at defined rotations (for example 5 subvolumes with 60° degree increments for C6 symmetry). Alignment was performed after the addition of symmetry related particles. The bottom left-most panel is a section through the spherical NEC lattice.