Permease involved in cell wall peptidoglycan recycling (PubMed:8878601, PubMed:12426329). Transports, from the periplasm into the cytoplasm, the disaccharide N-acetylglucosaminyl-beta-1,4-anhydro-N-acetylmuramic acid (GlcNAc-anhMurNAc) and GlcNAc-anhMurNAc-peptides (PubMed:12426329). Transport is dependent on the proton motive force (PubMed:12426329). AmpG is also involved in beta-lactamase induction (PubMed:7773404). Uptake is inhibited by carbonyl cyanide m-chlorophenylhydrazone (CCCP). Four hydrophobic segments are not embedded in the cytoplasmic membrane and form two large cytoplasmic loops. Belongs to the major facilitator superfamily.