Functional characterization of mouse cation transporter mOCT2 compared with mOCT1

Mari Kakehi, Noriko Koyabu, Takanori Nakamura, Takeshi Uchiumi, Michihiko Kuwano, Hisakazu Ohtani, Yasufumi Sawada

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22 Citations (Scopus)

Abstract

We characterized the function of mouse organic cation transporter OCT2 (TC 2.A.19.1.5) in comparison with that of OCT1 (TC 2.A.19.1.1). Uptake of [3H]1-methyl-4-phenylpyridinium ([3H]MPP+) by Xenopus laevis oocytes injected with mOCT1 (Slc22a1) or mOCT2 (Slc22a2) cRNA was attenuated by an increase of extracellular K+ concentration and under acidic extracellular conditions. The uptakes of [3H]MPP+ via mOCT1 and mOCT2 were saturable, with similar Michaelis constants (Kt) of 10 and 24 μM, respectively. mOCT2 also mediated the uptake of [14C]tetraethylammonium with a Kt value of 36 μM, which is similar to that of mOCT1. Quinine, tetraethylammonium, cimetidine, procainamide, choline, and N′-methylnicotinamide inhibited the uptake of [3H]MPP+ via mOCT1, as well as via mOCT2, and the inhibitory potencies for mOCT1 were comparable to but slightly higher than those for mOCT2. Thus, although the transport properties of mOCT2 are similar to those of mOCT1 in respect to the membrane-potential dependency, pH-sensitivity, and affinities for MPP+ and tetraethylammonium, several organic cations had weaker inhibitory effects on [3H]MPP+ uptake by mOCT2 than by mOCT1.

Original languageEnglish
Pages (from-to)644-650
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume296
Issue number3
DOIs
Publication statusPublished - 2002 Oct 14
Externally publishedYes

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Keywords

  • 1-Methyl-4-phenylpyridinium
  • Mouse organic cation transporter 1
  • Mouse organic cation transporter 2
  • Tetraethylammonium

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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