Uniporter involved in the facilitative transport of nucleosides and nucleobases, and contributes to maintaining their cellular homeostasis (     ). Functions as a Na(+)-independent transporter . Involved in the transport of nucleosides such as adenosine, guanosine, inosine, uridine, thymidine and cytidine (   , ). Also transports purine nucleobases (hypoxanthine, adenine, guanine) and pyrimidine nucleobases (thymine, uracil) (, ). Mediates basolateral nucleoside uptake into Sertoli cells, thereby regulating the transport of nucleosides in testis across the blood-testis barrier (By similarity). Regulates inosine levels in brown adipocytes tissues (BAT) and extracellular inosine levels, which controls BAT-dependent energy expenditure .
Subcellular locations: Basolateral cell membrane, Apical cell membrane, Cell membrane
Localized to the basolateral membrane of Sertoli cells . Localized to the cell membrane of erythrocytes (, ).
Expressed in testis at the blood-testis barrier (at protein level) . Detected in erythrocytes (at protein level) (, ). Expressed at relatively high levels in cerebral cortex, particularly the frontal and parietal lobes, and the thalamus and basal ganglia (at protein level) . In the midbrain expressed at moderate levels, whereas in the other areas of the brainstem, namely medulla and pons, cerebellum and the hippocampus expressed at lower amounts when compared to the other brain regions (at protein level) . Expressed in Langerhans cells and lymphocytes in the pancreas (at protein level) . Expressed in kidney, in polarized renal epithelial cells . Expressed in adipose tissues . Expressed in placenta . Expressed in small intestine .