Genomic organization and functional characterization of the human concentrative nucleoside transporter-3 isoform (hCNT3) expressed in mammalian cells

Human CNT3 encodes the concentrative nucleoside transport N3 system. Previous expression studies in oocytes showed that the K m values for nucleosides of the cloned hCNT3 were 7- to 25-fold lower than the endogenous N3 transporter in HL60 cells. Therefore, in the present study we re-examined the kinetic properties of the cloned hCNT3 using mammalian cell expression systems by transient expression in Cos7L cells and stably expression in nucleoside transporter deficient PK15NTD cells. We demonstrated that hCNT3 is a Na-dependent, broadly-selective nucleoside transporter with affinities (