Full metadata record
DC Field | Value | Language |
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dc.creator | Larrayoz, I.M. (Ignacio M.) | - |
dc.creator | Casado, F.J. (F. Javier) | - |
dc.creator | Pastor-Anglada, M. (Marçal) | - |
dc.creator | Lostao, M.P. (María Pilar) | - |
dc.date.accessioned | 2012-03-12T17:12:57Z | - |
dc.date.available | 2012-03-12T17:12:57Z | - |
dc.date.issued | 2004 | - |
dc.identifier.citation | Larrayoz IM, Casado FJ, Pastor-Anglada M, Lostao MP. Electrophysiological characterization of the human na(+)/nucleoside cotransporter 1 (hCNT1) and role of adenosine on hCNT1 function. J Biol Chem. 2004 Mar 5;279(10):8999-9007. | es_ES |
dc.identifier.issn | 0021-9258 | - |
dc.identifier.uri | https://hdl.handle.net/10171/21123 | - |
dc.description.abstract | We previously reported that the human Na(+)/nucleoside transporter pyrimidine-preferring 1 (hCNT1) is electrogenic and transports gemcitabine and 5'-deoxy-5-fluorouridine, a precursor of the active drug 5-fluorouracil. Nevertheless, a complete electrophysiological characterization of the basic properties of hCNT1-mediated translocation has not been performed yet, and the exact role of adenosine in hCNT1 function has not been addressed either. In the present work we have used the two-electrode voltage clamp technique to investigate hCNT1 transport mechanism and study the kinetic properties of adenosine as an inhibitor of hCNT1. We show that hCNT1 exhibits presteady-state currents that disappear upon the addition of adenosine or uridine. Adenosine, a purine nucleoside described as a substrate of the pyrimidine-preferring transporters, is not a substrate of hCNT1 but a high affinity blocker able to inhibit uridine-induced inward currents, the Na(+)-leak currents, and the presteady-state currents, with a K(i) of 6.5 microM. The kinetic parameters for uridine, gemcitabine, and 5'-deoxy-5-fluorouridine were studied as a function of membrane potential; at -50 mV, K(0.5) was 37, 18, and 245 microM, respectively, and remained voltage-independent. I(max) for gemcitabine was voltage-independent and accounts for approximately 40% that for uridine at -50 mV. Maximal current for 5'-DFUR was voltage-dependent and was approximately 150% that for uridine at all membrane potentials. K(0.5)(Na(+)) for Na(+) was voltage-independent at hyperpolarized membrane potentials (1.2 mM at -50 mV), whereas I(max)(Na(+)) was voltage-dependent, increasing 2-fold from -50 to -150 mV. Direct measurements of (3)H-nucleoside or (22)Na fluxes with the charge-associated revealed a ratio of two positive inward charges per nucleoside and one Na(+) per positive inward charge, suggesting a stoichiometry of two Na(+)/nucleoside. | es_ES |
dc.language.iso | eng | es_ES |
dc.publisher | American Society for Biochemistry and Molecular Biology | es_ES |
dc.rights | info:eu-repo/semantics/openAccess | es_ES |
dc.subject | Xenopus-Laevis oocytes | es_ES |
dc.subject | NA+ glucose cotransporter | es_ES |
dc.subject | Nucleoside transporter | es_ES |
dc.subject | Electrogenic properties | es_ES |
dc.subject | Mammalina cells | es_ES |
dc.subject | Pyrimidine | es_ES |
dc.title | Electrophysiological characterization of the human Na(+)/nucleoside cotransporter 1 (hCNT1) and role of adenosine on hCNT1 function. | es_ES |
dc.type | info:eu-repo/semantics/article | es_ES |
dc.type.driver | info:eu-repo/semantics/article | es_ES |
dc.identifier.doi | http://dx.doi.org/10.1074/jbc.M311940200 | es_ES |
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