Extended Data Fig. 1: Details in the PTC of prior structures.
a, Close-up of the PTC in PDB 7K00 illustrates the poor quality of local density in this map (indigo) around the P site (rose) and A site (green) tRNAs. PTC bases U2506, U2585, and A2602 of the 23S rRNA are shown in white. The deposited 50S-focused map is shown with an additional B-factor of 30 Å2 applied, supersampled for smoothness. b, Close-up of the PTC in PDB 6XZ7, showing dipeptide in the A site (green with atomistic coloring) and uncharged P-site tRNA (rose). The map has been supersampled for smoothness. Contour levels for maps shown in both a and b are chosen to illustrate disorder relative to better-resolved map regions, but lower contour levels and/or higher B-factor blurring brings out features supporting models. Labels for A- and P-site tRNAs in a and b are color-matched to the carbon atoms, and 23S rRNA bases are labeled in black. c, P-site tRNA A76 backbone conformation in our model (pink, black outline) compared to 6XZ7 (light gray) and 1VY4 (dark gray). Labels indicating the models are color-matched to the carbon atoms.
