Abstract
We report here the isolation, functional characterization, tissue distribution, and membrane localization of rat renal Na+-dicarboxylate transporter (rNaDC-1). rNaDC-1 consists of 2,245 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 tricarboxylates. 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 kidney and the small and large intestines. Immunohistochemistry using polyclonal antibodies raised against the 14 amino acids at the COOH terminus of rNaDC-1 revealed that rNaDC-1 is localized exclusively in the luminal membrane of S2 and S3.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Biological Transport / drug effects
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Carrier Proteins / chemistry
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Carrier Proteins / genetics*
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Carrier Proteins / metabolism
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Cell Membrane / metabolism
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Cloning, Molecular
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DNA, Complementary
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Dicarboxylic Acid Transporters*
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Dicarboxylic Acids / pharmacology
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Gene Library
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Humans
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Kidney / metabolism*
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Kidney Cortex / metabolism
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Kidney Medulla / metabolism
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Kinetics
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Membrane Proteins / chemistry
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Membrane Proteins / genetics*
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Membrane Proteins / metabolism
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Molecular Sequence Data
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Organic Anion Transporters, Sodium-Dependent*
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Rabbits
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Rats
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Recombinant Proteins / biosynthesis
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Recombinant Proteins / chemistry
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Recombinant Proteins / metabolism
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Sequence Alignment
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Sequence Homology, Amino Acid
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Succinates / metabolism
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Symporters*
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Tricarboxylic Acids / pharmacology
Substances
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Carrier Proteins
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DNA, Complementary
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Dicarboxylic Acid Transporters
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Dicarboxylic Acids
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Membrane Proteins
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Organic Anion Transporters, Sodium-Dependent
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Recombinant Proteins
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SLC13A2 protein, human
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Slc13a2 protein, rat
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Succinates
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Symporters
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Tricarboxylic Acids