Sodium-dependent and pyrimidine-selective transporter. Exhibits the transport characteristics of the nucleoside transport system cit or N2 subtype (N2/cit) (selective for pyrimidine nucleosides and adenosine). Transports uridine, cytidine, thymidine, and nucleoside-derived drugs. adenosine(out) + Na(+)(out) = adenosine(in) + Na(+)(in) Na(+)(out) + uridine(out) = Na(+)(in) + uridine(in) Na(+)(out) + thymidine(out) = Na(+)(in) + thymidine(in) cytidine(out) + Na(+)(out) = cytidine(in) + Na(+)(in) Belongs to the concentrative nucleoside transporter (CNT) (TC 2.A.41) family.