Equilibrative Nucleoside Transporter 2 (ENT2)

The uptake of nucleosides by transporters, such as SLC29A2, is essential for nucleotide synthesis by salvage pathways in cells that lack de novo biosynthetic pathways. Nucleoside transport also plays a key role in the regulation of many physiologic processes through its effect on adenosine concentration at the cell surface. The nucleotide sequences of ENT2 and HNP36 are identical except for a 68-nucleotide insertion in ENT2 following nucleotide 337 of HNP36. The deduced 456-amino acid ENT2 protein has a calculated molecular mass of 50.2 kD and shares 46% amino acid identity with ENT1 (SLC29A1). It has 11 transmembrane (TM) domains connected to one another by hydrophilic loops. Most of the loops are small, except for 2 large loops connecting TM domains 1 and 2 and TM domains 6 and 7.