A family (SLC28) of sodium dependent transporters (concentrative nucleoside transporters) that operate in conjunction with the equilibrative (sodium-independent) transporters (ENTs), although they belong to structurally unrelated protein families. There are three subtypes, CNT1, CNT2, and CNT3 (SLC28A1, SLC28A2, and SLC28A3, respectively), that transport both naturally occurring nucleosides and synthetic nucleoside analogues used in chemotherapy. CNT1 (649 aa), found primarily in epithelia, is pyrimidine-nucleoside preferring; CNT2 (658 aa) is purine-nucleoside preferring; and CNT3 (691 aa) transports both pyrimidine and purine nucleosides. The latter two are more widely distributed in tissues. They are important in nucleotide salvage pathways.
Subjects: Medicine and Health.