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- Title
Identification and properties of a novel variant of NBC4 (Na<sup>+</sup> /HCO<sup>-</sup><sub>3</sub> co-transporter 4) that is predominantly expressed in the choroid plexus.
- Authors
FUKUDA, Hidekazu; HIRATA, Taku; NAKAMURA, Nobuhiro; KATO, Akira; KAWAHARA, Katsumasa; WAKABAYASHI, Shigeo; CHANG, Min-Hwang; ROMERO, Michael F.; HIROSE, Shigehisa
- Abstract
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 HCO3- 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.
- Subjects
CHOROID plexus; EPITHELIAL cells; CEREBROSPINAL fluid; SODIUM bicarbonate; LABORATORY rats; EPITHELIUM
- Publication
Biochemical Journal, 2013, Vol 450, Issue 1, p179
- ISSN
0264-6021
- Publication type
Article
- DOI
10.1042/BJ20121515