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

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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	Unknown	Substrate	Details