Rescues stalled ribosomes (PubMed:21418110, PubMed:21051357, PubMed:22922063). Can hydrolyze peptidyl-tRNA on ribosomes stalled by both non-stop mRNAs and mRNAs that contain rare codon clusters (PubMed:21051357) or ribosomes stalled in the middle of mRNA (PubMed:22922063). First identified as a complementary ribosome rescue system when the stalled ribosome cannot be rescued by the SsrA(tmRNA)-SmpB quality control system or the alternative ribosome-rescue factor A (arfA) (PubMed:21418110). an N-acyl-L-alpha-aminoacyl-tRNA + H2O = a tRNA + an N-acyl-L-amino acid + H(+) Associated with 70S ribosomes and polysomes. The unstructured C-terminal region is required for ribosome binding and peptidyl-tRNA hydrolase activity. The C-terminal tail functions as a sensor to discriminate between stalled and actively translating ribosomes by binding in the mRNA entry channel downstream of the A site between the head and shoulder of the 30S subunit. This allows the N-terminal globular domain to sample different conformations, so that its conserved GGQ motif is optimally positioned in the peptidyltransferase center (PTC) to catalyze the hydrolysis of peptidyl-tRNA. The N-terminal domain of ArfB is bound in the A site of the 50S subunit next to the P-site tRNA. Belongs to the prokaryotic/mitochondrial release factor family.