Proton-coupled amino-acid transporter that transports free histidine and certain di- and tripeptides, and is involved in innate immune response (By similarity). Also able to transport carnosine (PubMed:31073693). Involved in the detection of microbial pathogens by toll-like receptors (TLRs) and NOD-like receptors (NLRs), probably by mediating transport of bacterial peptidoglycans across the endolysosomal membrane: catalyzes the transport of certain bacterial peptidoglycans, such as muramyl dipeptide (MDP), the NOD2 ligand (By similarity). H(+)(out) + L-histidine(out) = H(+)(in) + L-histidine(in) a dipeptide(out) + H(+)(out) = a dipeptide(in) + H(+)(in) H(+)(out) + N-acetylmuramyl-L-alanyl-D-isoglutamine(out) = H(+)(in) + N-acetylmuramyl-L-alanyl-D-isoglutamine(in) carnosine(out) + H(+)(out) = carnosine(in) + H(+)(in) Belongs to the major facilitator superfamily. Proton-dependent oligopeptide transporter (POT/PTR) (TC 2.A.17) family.