Nucleoside transporter that functions as a pyrimidine nucleoside carrier in all organs. Has high affinity for adenosine and uridine when expressed in a heterologous system (yeast). Mediates proton-dependent adenosine or uridine transport in Xenopus oocytes. Plasma membrane. Expressed in root tips, vasculature of roots and leaves, and meristems of leaf primordia. Expressed in flowers and siliques. By nitrogen deficiency and 5-fluorouracil plus methotrexate. The isolated apoplastic sap extracted from the double mutant missing both NSH3 and ENT3 lacks the ability to catalyze the conversion of inosine in hypoxanthine; this double mutant is unable to grow on medium containing inosine as sole nitrogen source, in addition plants are more sensitive to the necrotrophic fungus Botrytis cinerea BMM but are resistant to the cytotoxic adenosine analog 2-chloro-adenosine (CADO) and to 5-fluoro-uridine. Belongs to the SLC29A/ENT transporter (TC 2.A.57) family.