Sodium-dependent, pyrimidine- and purine-selective (PubMed:11032837). Involved in the homeostasis of endogenous nucleosides (PubMed:11032837). Exhibits the transport characteristics of the nucleoside transport system cib or N3 subtype (N3/cib) (with marked transport of both thymidine and inosine) (PubMed:11032837). Employs a 2:1 sodium/nucleoside ratio (PubMed:11032837). Also able to transport gemcitabine, 3'-azido-3'-deoxythymidine (AZT), ribavirin and 3-deazauridine (By similarity). 2 Na(+)(out) + thymidine(out) = 2 Na(+)(in) + thymidine(in) cytidine(out) + 2 Na(+)(out) = cytidine(in) + 2 Na(+)(in) 2 Na(+)(out) + uridine(out) = 2 Na(+)(in) + uridine(in) adenosine(out) + 2 Na(+)(out) = adenosine(in) + 2 Na(+)(in) guanosine(out) + 2 Na(+)(out) = guanosine(in) + 2 Na(+)(in) inosine(out) + 2 Na(+)(out) = inosine(in) + 2 Na(+)(in) Homotrimer. Belongs to the concentrative nucleoside transporter (CNT) (TC 2.A.41) family.