Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
J Physiol
2004 Aug 01;558Pt 3:807-23. doi: 10.1113/jphysiol.2004.068189.
Show Gene links
Show Anatomy links
Electrophysiological characterization of a recombinant human Na+-coupled nucleoside transporter (hCNT1) produced in Xenopus oocytes.
Smith KM
,
Ng AM
,
Yao SY
,
Labedz KA
,
Knaus EE
,
Wiebe LI
,
Cass CE
,
Baldwin SA
,
Chen XZ
,
Karpinski E
,
Young JD
.
???displayArticle.abstract???
Human concentrative nucleoside transporter 1 (hCNT1) mediates active transport of nucleosides and anticancer and antiviral nucleoside drugs across cell membranes by coupling influx to the movement of Na(+) down its electrochemical gradient. The two-microelectrode voltage-clamp technique was used to measure steady-state and presteady-state currents of recombinant hCNT1 produced in Xenopus oocytes. Transport was electrogenic, phloridzin sensitive and specific for pyrimidine nucleosides and adenosine. Nucleoside analogues that induced inwardly directed Na(+) currents included the anticancer drugs 5-fluorouridine, 5-fluoro-2'-deoxyuridine, cladribine and cytarabine, the antiviral drugs zidovudine and zalcitabine, and the novel thymidine mimics 1-(2-deoxy-beta-d-ribofuranosyl)-2,4-difluoro-5-methylbenzene and 1-(2-deoxy-beta-d-ribofuranosyl)-2,4-difluoro-5-iodobenzene. Apparent K(m) values for 5-fluorouridine, 5-fluoro-2'-deoxyuridine and zidovudine were 18, 15 and 450 microm, respectively. hCNT1 was Na(+) specific, and the kinetics of steady-state uridine-evoked Na(+) currents were consistent with an ordered simultaneous transport model in which Na(+) binds first followed by uridine. Membrane potential influenced both ion binding and carrier translocation. The Na(+)-nucleoside coupling stoichiometry, determined directly by comparing the uridine-induced inward charge movement to [(14)C]uridine uptake was 1: 1. hCNT1 presteady-state currents were used to determine the fraction of the membrane field sensed by Na(+) (61%), the valency of the movable charge (-0.81) and the average number of transporters present in the oocyte plasma membrane (6.8 x 10(10) per cell). The hCNT1 turnover rate at -50 mV was 9.6 molecules of uridine transported per second.
Acimovic,
Molecular evolution of the equilibrative nucleoside transporter family: identification of novel family members in prokaryotes and eukaryotes.
2002, Pubmed
Acimovic,
Molecular evolution of the equilibrative nucleoside transporter family: identification of novel family members in prokaryotes and eukaryotes.
2002,
Pubmed
Baldwin,
The equilibrative nucleoside transporter family, SLC29.
2004,
Pubmed
Baldwin,
Nucleoside transporters: molecular biology and implications for therapeutic development.
1999,
Pubmed
Bassilana,
Facilitated diffusion properties of melibiose permease in Escherichia coli membrane vesicles. Release of co-substrates is rate limiting for permease cycling.
1987,
Pubmed
Birnir,
Voltage-clamp studies of the Na+/glucose cotransporter cloned from rabbit small intestine.
1991,
Pubmed
,
Xenbase
Che,
Primary structure and functional expression of a cDNA encoding the bile canalicular, purine-specific Na(+)-nucleoside cotransporter.
1995,
Pubmed
Chen,
Stoichiometry and kinetics of the high-affinity H+-coupled peptide transporter PepT2.
1999,
Pubmed
,
Xenbase
Chen,
Fast voltage clamp discloses a new component of presteady-state currents from the Na(+)-glucose cotransporter.
1996,
Pubmed
,
Xenbase
Chen,
Thermodynamic determination of the Na+: glucose coupling ratio for the human SGLT1 cotransporter.
1995,
Pubmed
,
Xenbase
Chen,
Characterization of a rat Na+-dicarboxylate cotransporter.
1998,
Pubmed
,
Xenbase
Craig,
Cloning of the nupC gene of Escherichia coli encoding a nucleoside transport system, and identification of an adjacent insertion element, IS 186.
1994,
Pubmed
Crawford,
Cloning of the human equilibrative, nitrobenzylmercaptopurine riboside (NBMPR)-insensitive nucleoside transporter ei by functional expression in a transport-deficient cell line.
1998,
Pubmed
de Koning,
Adenosine transporters in bloodstream forms of Trypanosoma brucei brucei: substrate recognition motifs and affinity for trypanocidal drugs.
1999,
Pubmed
Díez-Sampedro,
Na+-to-sugar stoichiometry of SGLT3.
2001,
Pubmed
,
Xenbase
Dresser,
Electrophysiological analysis of the substrate selectivity of a sodium-coupled nucleoside transporter (rCNT1) expressed in Xenopus laevis oocytes.
2000,
Pubmed
,
Xenbase
Eskandari,
Thyroid Na+/I- symporter. Mechanism, stoichiometry, and specificity.
1997,
Pubmed
,
Xenbase
Fang,
Functional characterization of a recombinant sodium-dependent nucleoside transporter with selectivity for pyrimidine nucleosides (cNT1rat) by transient expression in cultured mammalian cells.
1996,
Pubmed
Fredholm,
Adenosine and neuroprotection.
1997,
Pubmed
Gomez-Angelats,
Hormonal regulation of concentrative nucleoside transport in liver parenchymal cells.
1996,
Pubmed
Graham,
Differential transport of cytosine-containing nucleosides by recombinant human concentrative nucleoside transporter protein hCNT1.
2000,
Pubmed
Griffith,
Nucleoside and nucleobase transport systems of mammalian cells.
1996,
Pubmed
Hamilton,
Subcellular distribution and membrane topology of the mammalian concentrative Na+-nucleoside cotransporter rCNT1.
2001,
Pubmed
,
Xenbase
Hazama,
Presteady-state currents of the rabbit Na+/glucose cotransporter (SGLT1).
1997,
Pubmed
,
Xenbase
Hirayama,
Common mechanisms of inhibition for the Na+/glucose (hSGLT1) and Na+/Cl-/GABA (hGAT1) cotransporters.
2001,
Pubmed
,
Xenbase
Hirayama,
Protons drive sugar transport through the Na+/glucose cotransporter (SGLT1).
1994,
Pubmed
,
Xenbase
Huang,
Functional expression of Na(+)-dependent nucleoside transport systems of rat intestine in isolated oocytes of Xenopus laevis. Demonstration that rat jejunum expresses the purine-selective system N1 (cif) and a second, novel system N3 having broad specificity for purine and pyrimidine nucleosides.
1993,
Pubmed
,
Xenbase
Huang,
Cloning and functional expression of a complementary DNA encoding a mammalian nucleoside transport protein.
1994,
Pubmed
,
Xenbase
Hyde,
The ENT family of eukaryote nucleoside and nucleobase transporters: recent advances in the investigation of structure/function relationships and the identification of novel isoforms.
2001,
Pubmed
Jauch,
Electrogenic properties of the sodium-alanine cotransporter in pancreatic acinar cells: II. Comparison with transport models.
1986,
Pubmed
Klamo,
Kinetics and stoichiometry of a proton/myo-inositol cotransporter.
1996,
Pubmed
,
Xenbase
Larráyoz,
Electrophysiological characterization of the human Na(+)/nucleoside cotransporter 1 (hCNT1) and role of adenosine on hCNT1 function.
2004,
Pubmed
Lee,
Na+- and K+-dependent uridine transport in rat renal brush-border membrane vesicles.
1988,
Pubmed
Lee,
The high affinity Na+/glucose cotransporter. Re-evaluation of function and distribution of expression.
1994,
Pubmed
,
Xenbase
Liman,
Subunit stoichiometry of a mammalian K+ channel determined by construction of multimeric cDNAs.
1992,
Pubmed
,
Xenbase
Lin,
Synthesis of [3H]phlorizin and its binding behavior to renal brush-border membranes.
1983,
Pubmed
Loewen,
Identification of amino acid residues responsible for the pyrimidine and purine nucleoside specificities of human concentrative Na(+) nucleoside cotransporters hCNT1 and hCNT2.
1999,
Pubmed
,
Xenbase
Loewen,
Functional characterization of a H+/nucleoside co-transporter (CaCNT) from Candida albicans, a fungal member of the concentrative nucleoside transporter (CNT) family of membrane proteins.
2003,
Pubmed
,
Xenbase
Loo,
Relaxation kinetics of the Na+/glucose cotransporter.
1993,
Pubmed
,
Xenbase
Lostao,
Electrogenic uptake of nucleosides and nucleoside-derived drugs by the human nucleoside transporter 1 (hCNT1) expressed in Xenopus laevis oocytes.
2000,
Pubmed
,
Xenbase
Mackenzie,
Mechanisms of the human intestinal H+-coupled oligopeptide transporter hPEPT1.
1996,
Pubmed
,
Xenbase
Mackenzie,
Biophysical characteristics of the pig kidney Na+/glucose cotransporter SGLT2 reveal a common mechanism for SGLT1 and SGLT2.
1996,
Pubmed
,
Xenbase
Mackenzie,
Relationships between Na+/glucose cotransporter (SGLT1) currents and fluxes.
1998,
Pubmed
,
Xenbase
Mackey,
Gemcitabine transport in xenopus oocytes expressing recombinant plasma membrane mammalian nucleoside transporters.
1999,
Pubmed
,
Xenbase
Mackey,
Nucleoside transport and its significance for anticancer drug resistance.
1998,
Pubmed
Mager,
Steady states, charge movements, and rates for a cloned GABA transporter expressed in Xenopus oocytes.
1993,
Pubmed
,
Xenbase
Möhlmann,
Characterisation of a concentrative type of adenosine transporter from Arabidopsis thaliana (ENT1,At).
2001,
Pubmed
Novakova,
Identification of a region critically involved in the interaction of phlorizin with the rabbit sodium-D-glucose cotransporter SGLT1.
2001,
Pubmed
Panayotova-Heiermann,
Sodium/D-glucose cotransporter charge movements involve polar residues.
1994,
Pubmed
,
Xenbase
Panayotova-Heiermann,
Kinetics of steady-state currents and charge movements associated with the rat Na+/glucose cotransporter.
1995,
Pubmed
,
Xenbase
Parent,
Electrogenic properties of the cloned Na+/glucose cotransporter: II. A transport model under nonrapid equilibrium conditions.
1992,
Pubmed
Parent,
Electrogenic properties of the cloned Na+/glucose cotransporter: I. Voltage-clamp studies.
1992,
Pubmed
,
Xenbase
Perigaud,
Equal inhibition of the replication of human immunodeficiency virus in human T-cell culture by ddA bis(SATE)phosphotriester and 3'-azido-2',3'-dideoxythymidine.
1994,
Pubmed
Ritzel,
Molecular identification and characterization of novel human and mouse concentrative Na+-nucleoside cotransporter proteins (hCNT3 and mCNT3) broadly selective for purine and pyrimidine nucleosides (system cib).
2001,
Pubmed
,
Xenbase
Ritzel,
Molecular cloning and functional expression of cDNAs encoding a human Na+-nucleoside cotransporter (hCNT1).
1997,
Pubmed
,
Xenbase
Ritzel,
Molecular cloning, functional expression and chromosomal localization of a cDNA encoding a human Na+/nucleoside cotransporter (hCNT2) selective for purine nucleosides and uridine.
1998,
Pubmed
,
Xenbase
Shryock,
Adenosine and adenosine receptors in the cardiovascular system: biochemistry, physiology, and pharmacology.
1997,
Pubmed
Smith,
Electrophysiological characterization of a recombinant human Na+-coupled nucleoside transporter (hCNT1) produced in Xenopus oocytes.
2004,
Pubmed
,
Xenbase
Tsuchiya,
Cation-sugar cotransport in the melibiose transport system of Escherichia coli.
1978,
Pubmed
Vick,
Reevaluation of renal tubular glucose transport inhibition by phlorizin analogs.
1973,
Pubmed
Wadiche,
Kinetics of a human glutamate transporter.
1995,
Pubmed
,
Xenbase
Wang,
Synthesis of 1-(2-deoxy-beta-D-ribofuranosyl)-2,4-difluoro-5-substituted-benzene thymidine mimics, some related alpha-anomers, and their evaluation as antiviral and anticancer agents.
2001,
Pubmed
Wang,
Na(+)-dependent purine nucleoside transporter from human kidney: cloning and functional characterization.
1997,
Pubmed
,
Xenbase
Weiss,
The Hill equation revisited: uses and misuses.
1997,
Pubmed
Wielert-Badt,
Probing the conformation of the sugar transport inhibitor phlorizin by 2D-NMR, molecular dynamics studies, and pharmacophore analysis.
2000,
Pubmed
Williams,
Multiple sodium-dependent nucleoside transport systems in bovine renal brush-border membrane vesicles.
1991,
Pubmed
Wright,
Mechanisms of Na(+)-glucose cotransport.
1994,
Pubmed
,
Xenbase
Xiao,
A novel proton-dependent nucleoside transporter, CeCNT3, from Caenorhabditis elegans.
2001,
Pubmed
Yao,
Transport of antiviral 3'-deoxy-nucleoside drugs by recombinant human and rat equilibrative, nitrobenzylthioinosine (NBMPR)-insensitive (ENT2) nucleoside transporter proteins produced in Xenopus oocytes.
2001,
Pubmed
,
Xenbase
Yao,
Transport of adenosine by recombinant purine- and pyrimidine-selective sodium/nucleoside cotransporters from rat jejunum expressed in Xenopus laevis oocytes.
1996,
Pubmed
,
Xenbase
Yao,
Transport of the antiviral nucleoside analogs 3'-azido-3'-deoxythymidine and 2',3'-dideoxycytidine by a recombinant nucleoside transporter (rCNT) expressed in Xenopus laevis oocytes.
1996,
Pubmed
,
Xenbase
Yao,
An ancient prevertebrate Na+-nucleoside cotransporter (hfCNT) from the Pacific hagfish (Eptatretus stouti).
2002,
Pubmed
,
Xenbase
Yao,
Functional and molecular characterization of nucleobase transport by recombinant human and rat equilibrative nucleoside transporters 1 and 2. Chimeric constructs reveal a role for the ENT2 helix 5-6 region in nucleobase translocation.
2002,
Pubmed
,
Xenbase
Young,
Nucleoside transport in animal cells.
1983,
Pubmed
Zhang,
Uridine binding motifs of human concentrative nucleoside transporters 1 and 3 produced in Saccharomyces cerevisiae.
2003,
Pubmed
