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Na(+)-coupled transport of L-carnitine via high-affinity carnitine transporter OCTN2 and its subcellular localization in kidney.
Biochim Biophys Acta. 2001 Jun 06; 1512(2):273-84.BB

Abstract

The mechanism of Na(+)-dependent transport of L-carnitine via the carnitine/organic cation transporter OCTN2 and the subcellular localization of OCTN2 in kidney were studied. Using plasma membrane vesicles prepared from HEK293 cells that were stably transfected with human OCTN2, transport of L-carnitine via human OCTN2 was characterized. Uptake of L-[(3)H]carnitine by the OCTN2-expressing membrane vesicles was significantly increased in the presence of an inwardly directed Na(+) gradient, with an overshoot, while such transient uphill transport was not observed in membrane vesicles from cells that were mock transfected with expression vector pcDNA3 alone. The uptake of L-[(3)H]carnitine was specifically dependent on Na(+) and the osmolarity effect showed that Na(+) significantly influenced the transport rather than the binding. Changes of inorganic anions in the extravesicular medium and of membrane potential by valinomycin altered the initial uptake activity of L-carnitine by OCTN2. In addition, the fluxes of L-carnitine and Na(+) were coupled with 1:1 stoichiometry. Accordingly, it was clarified that Na(+) is coupled with flux of L-carnitine and the flux is an electrogenic process. Furthermore, OCTN2 was localized on the apical membrane of renal tubular epithelial cells. These results clarified that OCTN2 is important for the concentrative reabsorption of L-carnitine after glomerular filtration in the kidney.

Authors+Show Affiliations

Faculty of Pharmaceutical Sciences, Kanazawa University, Kanazawa, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

11406104

Citation

Tamai, I, et al. "Na(+)-coupled Transport of L-carnitine Via High-affinity Carnitine Transporter OCTN2 and Its Subcellular Localization in Kidney." Biochimica Et Biophysica Acta, vol. 1512, no. 2, 2001, pp. 273-84.
Tamai I, China K, Sai Y, et al. Na(+)-coupled transport of L-carnitine via high-affinity carnitine transporter OCTN2 and its subcellular localization in kidney. Biochim Biophys Acta. 2001;1512(2):273-84.
Tamai, I., China, K., Sai, Y., Kobayashi, D., Nezu, J., Kawahara, E., & Tsuji, A. (2001). Na(+)-coupled transport of L-carnitine via high-affinity carnitine transporter OCTN2 and its subcellular localization in kidney. Biochimica Et Biophysica Acta, 1512(2), 273-84.
Tamai I, et al. Na(+)-coupled Transport of L-carnitine Via High-affinity Carnitine Transporter OCTN2 and Its Subcellular Localization in Kidney. Biochim Biophys Acta. 2001 Jun 6;1512(2):273-84. PubMed PMID: 11406104.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Na(+)-coupled transport of L-carnitine via high-affinity carnitine transporter OCTN2 and its subcellular localization in kidney. AU - Tamai,I, AU - China,K, AU - Sai,Y, AU - Kobayashi,D, AU - Nezu,J, AU - Kawahara,E, AU - Tsuji,A, PY - 2001/6/19/pubmed PY - 2001/8/3/medline PY - 2001/6/19/entrez SP - 273 EP - 84 JF - Biochimica et biophysica acta JO - Biochim Biophys Acta VL - 1512 IS - 2 N2 - The mechanism of Na(+)-dependent transport of L-carnitine via the carnitine/organic cation transporter OCTN2 and the subcellular localization of OCTN2 in kidney were studied. Using plasma membrane vesicles prepared from HEK293 cells that were stably transfected with human OCTN2, transport of L-carnitine via human OCTN2 was characterized. Uptake of L-[(3)H]carnitine by the OCTN2-expressing membrane vesicles was significantly increased in the presence of an inwardly directed Na(+) gradient, with an overshoot, while such transient uphill transport was not observed in membrane vesicles from cells that were mock transfected with expression vector pcDNA3 alone. The uptake of L-[(3)H]carnitine was specifically dependent on Na(+) and the osmolarity effect showed that Na(+) significantly influenced the transport rather than the binding. Changes of inorganic anions in the extravesicular medium and of membrane potential by valinomycin altered the initial uptake activity of L-carnitine by OCTN2. In addition, the fluxes of L-carnitine and Na(+) were coupled with 1:1 stoichiometry. Accordingly, it was clarified that Na(+) is coupled with flux of L-carnitine and the flux is an electrogenic process. Furthermore, OCTN2 was localized on the apical membrane of renal tubular epithelial cells. These results clarified that OCTN2 is important for the concentrative reabsorption of L-carnitine after glomerular filtration in the kidney. SN - 0006-3002 UR - https://www.unboundmedicine.com/medline/citation/11406104/Na_+__coupled_transport_of_L_carnitine_via_high_affinity_carnitine_transporter_OCTN2_and_its_subcellular_localization_in_kidney_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0005273601003285 DB - PRIME DP - Unbound Medicine ER -