Figure 1. Transition state eEF2 on the 80S ribosome.

(a,b) Schematic representations of the transition state of GTP during hydrolysis. The terminal phosphate is in a planar configuration (a), which is mimicked by AlF₄⁻ in our structure (b).

(c) Gel electrophoresis analysis. eEF2 was incubated with Tlan80S in the presence of either GDP, GDP and Sordarin, or GDP and AlF₄⁻, and the amount of eEF2 bound following pelleting of ribosomes was quantified. The eEF2 band is indicated on the gel. The faster-migrating bands correspond to ribosomal proteins. (d) Cryo-EM reconstruction of the AlF₄ complex. The inset shows a close-up view of the intersubunit space with eEF2 (red) binding regions. Weak densities at the 40S (yellow) interacting regions are marked with dashed circles, and strong interactions of the domains G’ and V with the stalk base region of the 60S (blue) are marked with asterisks. Landmarks for 40S: lf, left foot; rf, right foot; sh, shoulder; and for 60S: CP, central protuberance; sb, stalk base; st, extended stalk. Densities corresponding to the different domains of eEF2 are marked.