Uniporter that mediates the facilitative transport of nucleoside across lysosomal and mitochondrial membranes ( , ). Functions as a non-electrogenic Na(+)-independent transporter ( ). Substrate transport is pH-dependent and enhanced under acidic condition, probably reflecting the location of the transporter in acidic intracellular compartments ( ). Proton is not a cotransporting ion but most likely change the ionization state of the transporter which dictates transport-permissible/impermissible conformation for nucleoside translocation . May direct the nucleoside transport from lysosomes to cytosol or cytosol to mitochondria to facilitate the fundamental function of salvage synthesis of nucleic acids . Involved in the transport of nucleosides (adenosine, guanosine, uridine, thymidine, cytidine and inosine) and deoxynucleosides (deoxyadenosine, deoxycytidine) ( , ). Also mediates transport of purine nucleobases (adenine, guanine) and pyrimidine nucleobases (uracil) (, ). Also able to transport monoamine neurotransmitters dopamine, serotonin, noradrenaline and tyramine . Capable of transporting ATP . Mediates nucleoside export from lysosomes in macrophages, which regulates macrophage functions and numbers (By similarity).
Subcellular locations: Lysosome membrane, Late endosome membrane, Mitochondrion membrane, Cell membrane
Observed in a punctate intracellular pattern showing partial colocalization with late endosomes/lysosomes . Detected at the cell surface only in certain placental cells .
Widely expressed in both adult and fetal tissues . Highest levels in placenta, uterus, ovary, spleen, lymph node and bone marrow . Expressed in liver . Lowest levels in brain and heart . Expressed in macrophages .