Catalyzes the GTP-dependent ribosomal translocation step during translation elongation. During this step, the ribosome changes from the pre-translocational (PRE) to the post-translocational (POST) state as the newly formed A-site-bound peptidyl-tRNA and P-site-bound deacylated tRNA move to the P and E sites, respectively. Catalyzes the coordinated movement of the two tRNA molecules, the mRNA and conformational changes in the ribosome. Component of the mRNA surveillance SURF complex, at least composed of ERF1, ERF3 (ERF3A or ERF3B), EEF2, UPF1/RENT1, SMG1, SMG8 and SMG9. Interacts with RBPMS2. Phosphorylation by CSK promotes cleavage and SUMOylation-dependent nuclear translocation of the C-terminal cleavage product. Phosphorylation by EF-2 kinase completely inactivates EF-2; it requires prior phosphorylation by CDK2 at Ser-595 during mitotic prometaphase. Phosphorylation by CSK promotes SUMOylation, proteolytic cleavage, and nuclear translocation if the C-terminal fragment. Diphthamide is 2-[3-carboxyamido-3-(trimethyl-ammonio)propyl]histidine (By similarity). ISGylated. Proteolytically processed at two sites following phosphorylation by CSK. SUMOylated following phosphorylation by CSK, promotes proteolytic cleavage. Belongs to the GTP-binding elongation factor family. EF-G/EF-2 subfamily.