FIGURE 1.

Cryo-EM structure of the 30S-inactivated-high-Mg²⁺ particle. (A) Front (top row) and back view (bottom row) of the cryo-EM maps obtained for the two subpopulations found for the 30S-inactivated-high-Mg²⁺ particle. The maps are shown side-by-side with the 30S subunit structure obtained by X-ray crystallography (30S canonical structure). This structure was obtained by generating a density map from PDB file 4V4Q and low-pass filtering this structure to 4 Å. The rRNA is displayed in light gray, the r-proteins in green, and helix 44 in goldenrod orange. The r-proteins uS2, uS7, and bS21 for which representative densities do not appear in the cryo-EM maps of the 30S-inactivated-high-Mg²⁺ particle are shown in blue in the map of the 30S subunit obtained by X-ray crystallography. These proteins and other landmarks of the 30S subunit are labeled. (B) Zoomed-in view of the decoding region of the cryo-EM maps obtained for the two subpopulations found for the 30S-inactivated-high-Mg²⁺ particle and the structure of the 30S subunit obtained by X-ray crystallography. The area visualized in this panel is indicated as a frame in panel A.