Identification and properties of a novel variant of NBC4 (Na +/HCO3- co-transporter 4) that is predominantly expressed in the choroid plexus

Hidekazu Fukuda, Taku Hirata, Nobuhiro Nakamura, Akira Kato, Katsumasa Kawahara, Shigeo Wakabayashi, Min Hwang Chang, Michael F. Romero, Shigehisa Hirose

Research output: Contribution to journalArticle

9 Scopus citations


Secretion of HCO3- at the apical side of the epithelial cells of the choroid plexus is an essential step in the formation of cerebrospinal fluid. Anion conductance with a high degree of HCO 3- permeability has been observed and suggested to be the major pathway for HCO3- transport across the apical membrane. Recently, it was found that NBC (Na+/HCO3 - co-transporter) 4, an electrogenic member of the NBC family, was expressed in the choroid plexus. We found that a novel variant of the NBC4 [NBC4g/Slc4a5 (solute carrier family 4, sodium bicarbonate cotransporter, member 5)] is almost exclusively expressed in the apical membrane of rat choroid plexus epithelium at exceptionally high levels. RNA interference-mediated knockdown allowed the functional demonstration that NBC4g is the major player in the HCO3- transport across the apical membrane of the choroid plexus epithelium. When combined with a recent observation that in choroid plexus epithelial cells electrogenic NBC operates with a stoichiometry of 3:1, the results of the present study suggest that NBC4g mediates the efflux of HCO3- and contributes to cerebrospinal fluid production.

Original languageEnglish (US)
Pages (from-to)179-187
Number of pages9
JournalBiochemical Journal
Issue number1
StatePublished - Feb 15 2013



  • Cerebrospinal fluid
  • Choroid plexus
  • Member 5 (Slc4a5)
  • Na/HCO co-transporter e2 (NBCe2)
  • Sodium bicarbonate co-transporter
  • Solute carrier family 4

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this