Carnitine/Organic Cation Transporter

Human OCTN2 (SLC22A5)

   Human OCTN2 is a sodium ion-dependent carnitine transporter, and is highly expressed at the apical membranes of proximal renal tubular cells in kidney and small intestinal epithelial cells.
  Carnitine transport via OCTN2 is reported to play an important role in fat metabolism in muscle, and deficiency of  OCTN2 is associated with carnitine deficiency disease.
   Human OCTN2 transports not only carnitine, but also various organic cations.

<References>
   Tamai I, Ohashi R, Nezu J, Yabuuchi H, Oku A, Shimane M, Sai Y, Tsuji A.(1998) Molecular and functional identification of sodium ion-dependent, high affinity human carnitine transporter OCTN2. J Biol Chem 273(32): 20378-20382.

   Ohashi R, Tamai I, Yabuuchi H, Nezu J, Oku A, Sai Y, Shimane M, Tsuji A.(1999) Na(+)-dependent carnitine transport by organic cation transporter (OCTN2): its pharmacological and toxicological relevance. J Pharmacol Exp Ther 291(2): 778-784.

   Nezu J, Tamai I, Oku A, Ohashi R, Yabuuchi H, Hashimoto N, Nikaido H, Sai Y, KoizumiA, Shoji Y, Takada G, Matsuishi T, Yoshino M, Kato H, Ohura T, Tsujimoto G, Hayakawa J, Shimane M, Tsuji A.(1999) Primary systemic carnitine deficiency is caused by mutations in a gene encoding sodium ion-dependent carnitine transporter. Nature Genetics 21(1): 91-94.

   Ohashi R, Tamai I, Nezu J, Nikaido H, Hashimoto N, Oku A, Sai Y, Shimane M, Tsuji A.(2001)　Molecular and physiological evidence for multifunctionality of carnitine/organic cation transporter OCTN2. Mol Pharmacol 59(2): 358-366.

  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 locarization in kidney. Biochim Biophys Acta 1512: 273-284.

  Kato Y, Sugiura M, Sugiura T, Wakayama T, Kubo Y, Kobayashi D, Sai Y, Tamai I, Iseki S, Tsuji A (2006) Organic cation/carnitine transporter OCTN2 (Slc22a5) is responsible for carnitine transport across apical membranes of small intestinal epithelial cells in mouse. Mol Pharmacol 70(3): 829-837.