Characterization and functional analysis of the promoter for the human equilibrative nucleoside transporter gene, hENT1.

Equilibrative nucleoside transporters (ENTs) are membrane proteins that transport nucleosides, nucleobases and analogs across membranes. ENT genes and the regulation of their expression are poorly understood. Therefore, we isolated and functionally characterized the promoter of the prototypic human ENT, hENT1. A single transcriptional initiation site 58 bp downstream of the TATA box and 272 bp upstream of the translation initiation site is present. Limited sequence similarity exists between the hENT1 and mouse ENT1 (mENT1) promoters suggesting conservation of ENT1 transcriptional regulators in mammals. Putative consensus sites for transcription factors exist within the hENT1 promoter. Reporter assays revealed similar but not identical transcriptional activity profiles in human cells.