Fig. 3. Docking of EF-Tu and aa-tRNA into the cryo-EM density of the ternary complex: (A) as seen from the solvent side; (B) as seen from the intersubunit side. (Views are similar, but not identical to those in Figure 2A and B.) Fitted atomic coordinates of E.coli EF-Tu (Song et al., 1999) and Phe-tRNAPhe [(from the ternary complex of T.aquaticus (Nissen et al., 1995)] are shown inside the semi-transparent cryo-EM density of the ternary complex. The domains of EF-Tu were fitted independently (domain I shown in green, domain II in yellow and domain III pink). The switch-I region within domain I is highlighted in cyan. The dotted line in (A) indicates the place of the kink in the anticodon arm of the tRNA. Orientations of the ribosome are shown as thumbnails on the left. SRL, α-sarcin–ricin loop; L11–rRNA (GAC), protein L11 and the segment of 58 nucleotides of the 23S rRNA, also known as the GTPase-associated center; S12, protein S12 from the small subunit; h5, helix 5 from the 16S rRNA; dc, decoding center in the A-site of the 30S subunit.