Extended Data Fig. 2: Comparison of the complete C. elegans ILS″ to a partial human ILS2.

a-b. Side-by-side comparison of the Ce ILS″ cryo-EM density map with the deposited human ILS2 map. Top: Overview, with cryo-EM density colored by subunits. For the human ILS2 (EMD-9647), a low pass filtered map (gaussian filter with a width of three standard deviations) is shown in addition (transparent white surface). Bottom: Zoom-ins to the spliceosomes core reveal nearly indistinguishable densities where high-resolution density is available for both Ce and Hs ILS. c. Coordinate model statistics for Ce ILS″ and Hs ILS2, listing number of residues included as full sidechain models or backbone models, respectively. Numbers in brackets indicate completeness relative to the sum of all residues calculated from deposited sequences for the full-length proteins. d. ILS subunit diagrams indicating which residues are included in coordinate models of the Ce ILS″ or Hs ILS2 as full side chain models (solid fill), backbone models (semi-transparent fill with stripes), or not modelled (transparent fill). Asterisks indicate severe register errors in deposited human ILS2 models in SYF1 (register error of up to 120 residues) and SYF3 (register error of ~20 residues).