<P> EF - Tu has been found in large quantities in the cytoskeletons of bacteria, co-localizing underneath the cell membrane with MreB, a cytoskeletal element that maintains cell shape . Defects in EF - Tu have been shown to result in defects in bacterial morphology . Additionally, EF - Tu has displayed some chaperone - like characteristics, with some experimental evidence suggesting that it promotes the refolding of a number of denatured proteins in vitro . </P> <P> EF - Tu is a monomeric protein with molecular weight around 43 kDa in Escherichia coli . The protein consists of three structural domains: a GTP - binding domain and two oligonucleotide - binding domains . The N - terminal domain I of EF - Tu is the GTP - binding domain . It consists of a six beta - strand core flanked by six alpha - helices . Domains II and III of EF - Tu, the oligonucleotide - binding domains, both adopt beta - barrel structures . </P> <P> 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 . </P> <P> Along with the ribosome, EF - Tu is one of the most important targets for antibiotic - mediated inhibition of translation . Antibiotics targeting EF - Tu can be categorized into one of two groups, depending on the mechanism of action, and one of four structural families . The first group includes the antibiotics pulvomycin and GE2270A, and inhibits the formation of the ternary complex . The second group includes the antibiotics kirromycin and enacyloxin, and prevents the release of EF - Tu from the ribosome after GTP hydrolysis . </P>

Except for the t-u exchange the trna anticodon is identical to