Cloning and characterization of a novel human pH-dependent organic cation transporter, OCTN1

Ikumi Tamai, Hikaru Yabuuchi, Jun Ichi Nezu, Yoshimichi Sai, Asuka Oku, Miyuki Shimane, Akira Tsuji

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393 Citations (Scopus)


cDNA for a novel proton/organic cation transporter, OCTN1, was cloned from human fetal liver and its transport activity was investigated. OCTN1 encodes a 551-amino acid protein with 11 transmembrane domains and one nucleotide binding site motif. It is strongly expressed in kidney, trachea, bone marrow and fetal liver and in several human cancer cell lines, but not in adult liver. When expressed in HEK293 cells, OCTN1 exhibited saturable and pH-dependent [3H]tetraethyl ammonium uptake with higher activity at neutral and alkaline pH than at acidic pH. Furthermore, treatment with metabolic inhibitors reduced the uptake, which is consistent with the presence of the nucleotide binding site sequence motif. Although its subcellular localization and detailed functional characteristics are not clear at present, OCTN1 appears to be a novel proton antiporter that functions for active secretion of cationic compounds across the renal epithelial brush-border membrane. It may play a role in the renal excretion of xenobiotics and their metabolites.

Original languageEnglish
Pages (from-to)107-111
Number of pages5
JournalFEBS Letters
Issue number1
Publication statusPublished - 08-12-1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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