Cryo-EM reconstructions of: a. wt-TSEN•pre-tRNA and b. endoX-TSEN•pre-tRNA, with cartoon overlays below. Due to its improved resolution, the endoX reconstruction was used to build and refine the overall structure. c. Model of the human TSEN complex at 0° and 90°, with overall dimensions of 116 × 79 × 65 Å. The subunits are colored as follows: TSEN54 (teal), TSEN34 (pink), TSEN2 (orange), TSEN15 (blue). The pre-tRNA is shaded in dark grey, with the intron in light grey.