The function of SLC28A3 (solute carrier family 28 member 3, Ensembl gene identifier ENSG00000197506) is as follows. Sodium-dependent, pyrimidine- and purine-selective (PubMed:11032837, PubMed:15861042, PubMed:16446384, PubMed:17140564, PubMed:21998139). Involved in the homeostasis of endogenous nucleosides (PubMed:11032837, PubMed:15861042). 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). Transports uridine (PubMed:21795683). Also able to transport gemcitabine, 3'-azido-3'-deoxythymidine (AZT), ribavirin and 3-deazauridine (PubMed:11032837, PubMed:17140564). {ECO:0000269|PubMed:11032837, ECO:0000269|PubMed:15861042, ECO:0000269|PubMed:16446384, ECO:0000269|PubMed:17140564, ECO:0000269|PubMed:21795683, ECO:0000269|PubMed:21998139}.