Extended Data Fig. 4: Interactions of eEF2 with the SSU body.

a, Comparison of the current X-ray structure of an early translocation intermediate (18S rRNA in cyan) with cryo-EM models of late translocation steps TI-POST1 (magenta, PDB ID 6GZ3) and TI-POST3 (grey, PDB ID 6GZ3)⁶. Superimposition of eEF2 in the two structures shows that there is a noticeable shift of 18S rRNA of the SSU body away from eEF2 at later stages of translocation. b, Contacts between eEF2 and h5 of SSU of the rotated ribosome in the reported intermediate translocation complex. c, Interactions between eEF2 and the SSU shoulder proteins eS30 and uS12. Stabilization of the eEF2 domain IV by the N-terminus of eukaryote-specific protein eS30 that itself interacts with conserved decoding protein uS12. Presumably, eS30 co-evolved with eEF2, whose domain IV has 65 additional amino acids compared to its bacterial counterpart EF-G⁵, to provide supplementary stabilization as well as to enhance propagation of conformational changes at the decoding site^13,14. d, A close up view of the dashed region from (c). Movement of uS12 (arrow 1) induced by the SSU body back-rotation can propagate to switch II (in cyan) of eEF2 through domain III (arrow 2) and can trigger GTP hydrolysis or Pi release. Regions of uS12 adjacent to eEF2 are shown and coloured dark- to light-green based on the rotational state where dark-green is the most rotated state (intermediate translocation complex) and medium (TI-POST1) and light (TI-POST3) greens represent the least rotated states. Alignment was done using eEF2.