Fig. 2.

Cryo‐EM reconstruction of the large subunit of Halococcus morrhuae. (A) The large subunit of Haloarcula marismotui (PDB: 1NJI) [49] is rigidly docked in the density obtained from 3D cryo‐EM reconstruction; 5S rRNA (purple), 23S rRNA (yellow), and uL5 and uL18 (orange‐red), and selected ribosomal other proteins (cyan) are shown; the insert is marked by *; Cp—central protuberance. The scale bar indicates 50 Å. (B) A view of the large subunit with the best‐available crystal structure docked in (PDB: 4V9F) [48] rotated to focus on the discordance in the helix 25 path (red arrow summarizing the crystal structure and green arrow summarizing the cryo‐EM structure). The cryo‐EM density at lower isosurface threshold is shown as an outline around the map, illustrating the continued projection of the helix. The P stalk can be seen on the left edge; though the P stalk proteins L11, L12, and L10e are visualized in the crystal structure of Haloarcula marismotui, they are not seen in this cryo‐EM map. Scale is identical to panel A. (C) Plot of the consistency of the two half‐maps after tight masking and mask correction. The 0.143 ‘gold‐standard’ cutoff is indicated as a dashed line.