Expression and localization of organic cation/carnitine transporter OCTN2 in Caco-2 cells.
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Elimrani I, Lahjouji K, Seidman E, Roy MJ, Mitchell GA, Qureshi I
Expression and localization of organic cation/carnitine transporter OCTN2 in Caco-2 cells.
Am J Physiol Gastrointest Liver Physiol. 2003 May;284(5):G863-71. Epub 2003 Jan 10.
- PubMed ID
- 12684216 [ View in PubMed]
- Abstract
l-Carnitine is derived both from dietary sources and biosynthesis. Dietary carnitine is absorbed in the small intestine and then distributed to other organs. Previous studies using Caco-2 cells demonstrated that the transport of l-carnitine in the intestine involves a carrier-mediated system. The purpose of this study was to determine whether the uptake of l-carnitine in Caco-2 cells is mediated by the recently identified organic cation/carnitine transporter (OCTN2). Kinetics of l-[(3)H]carnitine uptake were investigated with or without specific inhibitors. l-Carnitine uptake in mature cells was sodium dependent and linear with time. K(m) and V(max) values for saturable uptake were 14.07 +/- 1.70 micro M and 26.3 +/- 0.80 pmol. mg protein(-1). 6 min(-1), respectively. l-carnitine uptake was inhibited (P < 0.05-0.01) by valproate and other organic cations. Anti-OCTN2 antibodies recognized a protein in the brush-border membrane (BBM) of Caco-2 cells with an apparent molecular mass of 60 kDa. The OCTN2 expression was confirmed by double immunostaining. Our results demonstrate that l-carnitine uptake in differentiated Caco-2 cells is primarily mediated by OCTN2, located on the BBM.
DrugBank Data that Cites this Article
- Drug Transporters
Drug Transporter Kind Organism Pharmacological Action Actions Levocarnitine Solute carrier family 22 member 5 Protein Humans UnknownSubstrateDetails