 The GTP-binding domain I undergoes a dramatic conformational change upon GTP hydrolysis to GDP, allowing EF-Tu to dissociate from aa-tRNA and leave the ribosome.Reactivation of EF-Tu is achieved by GTP binding in the cytoplasm, which leads to a significant conformational change that reactivates the tRNA-binding site of EF-Tu.In particular, GTP binding to EF-Tu results in a ~90° rotation of domain I relative to domains II and III, exposing the residues of the tRNA-binding active site.