Cloning, functional characterization and localization of a rat
renal na+-dicarboxylate transporter.
Sekine, Takashi, Seok Ho Ch, Makoto Hosoyamada, Yoshikatsu Kanai,
Nobuaki Watanabe, Yoshitake Furuta, Kuniaki Fukuda, Takashi Igarashi,
and Hitoshi Endou.
Kyorin University School of Medicine, Department of Pharmacology
and Toxicology, Mitaka, Tokyo 181, Japan, Department of Pharmacology,
Catholic University Medical College, Banpo-dong 505, Seocho-gu, Seoul
137-701, Korea, Sankyo Co., Ltd., Drug Metabolism & Pharmacokinetics
IV Analytical and Metabolic Research Laboratories, Shinagawa-ku,
Tokyo 140, Japan, University of Tokyo Mejirodai Campus, Department of
Paediatrics, Bunkyo-ku, Tokyo 112, Japan
APStracts 5:0085F, 1998.
We report here the isolation, functional characterization, tissue
distribution and membrane localization of rat renal Na+-dicarboxylate
transporter (rNaDC-1). rNaDC-1 consists of 2245 nucleotides and the
deduced amino acid sequence showed 73 % and 75 % identity to rabbit
and human NaDC-1, respectively. When expressed in Xenopus laevis
oocytes, rNaDC-1 mediated sodium-dependent uptake of di- and tri
-carboxylates. Substrates of rNaDC-1 evoked inward currents in oocytes
expressed with rNaDC-1; succinate, [alpha]-ketoglutarate and
glutarate were relatively high affinity substrates and citrate was a
low affinity substrate of rNaDC-1. The coupling ratio of citrate to
charge was determined to be 1:1 at pH 7.4; influx of one positive
charge per citrate molecule suggests a symport of three Na+ with a
divalent citrate. Expression of rNaDC-1 mRNA was detected in the the
kidney and the small and large intestines. Immunohistochemistry using
polyclonal antibodies raised against the 14 amino acids at the C
-terminus of rNaDC-1 revealed that rNaDC-1 is localized exclusively in
the luminal membrane of S2 and S3.
Received 11 February 1998; accepted in final form 8 April 1998.
APS Manuscript Number F30-8.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 24 April 1998