cd03707

Domain III of elongation factor (EF) Tu. Ef-Tu consists of three structural domains, designated I, II and III. Domain III adopts a beta barrel structure. Domain III is involved in binding to both charged tRNA and binding to elongation factor Ts (EF-Ts). EF-Ts is the guanine-nucleotide-exchange factor for EF-Tu. EF-Tu and EF-G participate in the elongation phase during protein biosynthesis on the ribosome. Their functional cycles depend on GTP binding and its hydrolysis. The EF-Tu complexed with GTP and aminoacyl-tRNA delivers tRNA to the ribosome, whereas EF-G stimulates translocation, a process in which tRNA and mRNA movements occur in the ribosome. Crystallographic studies revealed structural similarities ("molecular mimicry") between tertiary structures of EF-G and the EF-Tu-aminoacyl-tRNA ternary complex. Domains III, IV, and V of EF-G mimic the tRNA structure in the EF-Tu ternary complex; domains III, IV and V can be related to the acceptor stem, anticodon helix and T stem of tRNA respectively.