A translation factor that gates the progression of the 70S ribosomal initiation complex (IC, containing tRNA(fMet) in the P-site) into the translation elongation cycle by using a mechanism sensitive to the ATP/ADP ratio. Binds to the 70S ribosome E-site where it modulates the state of the translating ribosome during subunit translocation. Stimulates dipeptide bond synthesis in the presence of ATP (cell in high energy state), but inhibits dipeptide synthesis in the presence of ADP (cell in low energy state), and thus may control translation in response to changing ATP levels (including during stationary phase). Following ATP hydrolysis is probably released allowing the ribosome to enter the elongation phase. ATPase activity is stimulated in the presence of ribosomes. Its specificity for the IC may be conferred by its recognition of features unique to tRNA(fMet). ATP + H2O = ADP + H(+) + phosphate Monomer at concentrations found in vivo, exists in a slowly reversible monomer-homodimer equilibrium. Probably contacts ribosomal proteins L1, L5, L33 and S7, the 16S and 23S rRNA and the P-site containing tRNA(fMet). Associates with ribosomes and polysomes. Constitutively expressed, increases in stationary phase (at protein level). The arm domain (residues 95-139) is inserted in the first ABC transporter domain. Its deletion abrogates the growth arrest and translation inhibition effect of the double Q-188/Q-470 mutation. When deleted impairs fitness in long-term (up to 6 days) growth in stationary phase (PubMed:24389466). Probably contacts ribosomal protein L1 (PubMed:24389465). The P-site tRNA interaction motif (PtIM domain, residues 242-322) probably interacts with the P-site tRNA(fMet) as well as the 23S rRNA. Not essential it can be disrupted, its absence impairs fitness in long-term (up to 6 days) growth in stationary phase. Belongs to the ABC transporter superfamily. ABCF family. Translational throttle EttA subfamily.