Figure 8.
CryoEM modeling of prp-8 suppressors in the context of the assembling human spliceosome. (A) Human spliceosome preB complex 6QX9 (9). The unstructured ACAGA box, anchored by the quasi-pseudoknot above and the U4/U6 helix below is represented by the bold dashed line. The 5′ss paired with U1snRNA is located just off the image to the lower right corner. (B) Human spliceosome B complex 6AHD (11). (C) Human spliceosome Bact complex 6FF4 (13). (D) Human spliceosome catalytic step 1 complex 5YZG (14). The coloring scheme for snu66, 27K, U4snRNA, U6snRNA, pre-mRNA, PRP8, RNF113A, YJU2, and ISY1 used in the images is indicated above the figures. PRP8 residues T524, D1549, and H1573 are labeled and shown as stick models, as are snu66 H765 and 27K M141 (we are using the C. elegans numbering imposed on their homologous positions in the human spliceosome). The G at the +1 and the U at the +2 positions of the intron, and the branchpoint A (bpA) are also labeled.