The recently solved structures of the protein elongation factor comple
xes, EF-Tu-CDPNP-phenylalanyl-tRNA and EF-Tu-Ts, complete the atomic p
rofile of four EF-Tu conformational states, As a set, the three-dimens
ional structures suggest an atomic model for movement during protein e
longation and, by molecular mimicry with EF-G, translocation as well.