This protein promotes the GTP-dependent binding of aminoacyl-tRNA to the A-site of ribosomes during protein biosynthesis. Monomer. Equally expressed in stationary and exponential phase (at protein level). Phosphorylated on serine and/or threonine residue(s), dephosphorylated by Stp. Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. EF-Tu/EF-1A subfamily.