The ENT family of eukaryote nucleoside and nucleobase transporters: recent advances in the investigation of structure/function relationships and the identification of novel isoforms.
The first examples of the equilibrative nucleoside transporter (ENT) family were characterized in human tissues at the molecular level only 4 years ago. Since that time, the identification of homologous proteins by functional cloning and genome analysis has revealed that the family is widely distributed in eukaryotes. Family members are predicted to possess 11 transmembrane helices (TMs), and recent investigations on the mammalian ENTs have implicated the TM 3-6 region in solute recognition. Whilst the name of the family reflects the properties of its prototypical member hENT1, an equilibrative transporter of nucleosides, some family members can also transport nucleobases and some are proton-dependent, concentrative transporters. In addition to their role in nucleoside salvage, ENTs are targets for coronary vasodilator drugs and act as routes for uptake of cytotoxic drugs in humans and protozoa. This paper summarizes current knowledge of the family and reports on the identification of a novel mammalian ENT isoform, designated ENT3, from mouse and human tissues.
Hyde
R J
RJ
School of Biochemistry and Molecular Biology, University of Leeds, UK.
Cass
C E
CE
Young
J D
JD
Baldwin
S A
SA
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D033705:Equilibrative Nucleoside Transport Proteins; D033721:Equilibrative Nucleoside Transporter 1; D006801:Humans; D049990:Membrane Transport Modulators; D026901:Membrane Transport Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D008956:Models, Chemical; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D020033:Protein Isoforms; D013329:Structure-Activity Relationship
D002352:Carrier Proteins; D033705:Equilibrative Nucleoside Transport Proteins; D033721:Equilibrative Nucleoside Transporter 1; D049990:Membrane Transport Modulators; D026901:Membrane Transport Proteins; D020033:Protein Isoforms; C438649:SLC29A1 protein, human