Crystal structure of the ERA-GNP-RNA complex (PDB entry 3IEV) and of the ERA-GDP complex (PDB entry 3IEU) are shown based on superimposed GTPase domains (Tu, Zhou, Tropea, Austin, Waugh, Court, and Ji. Proc. Natl. Acad. Sci. USA 2099; 106:14843-14848. Abstract).