Cloning, functional characterization, and localization of a rat renal Na+-dicarboxylate transporter.
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.
Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo 181, Japan.
T
T
Sekine
S H
SH
Cha
M
M
Hosoyamada
Y
Y
Kanai
N
N
Watanabe
Y
Y
Furuta
K
K
Fukuda
T
T
Igarashi
H
H
Endou
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D029382:Dicarboxylic Acid Transporters; D003998:Dicarboxylic Acids / Q000494:pharmacology; D015723:Gene Library; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D029363:Organic Anion Transporters, Sodium-Dependent; D011817:Rabbits; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013386:Succinates / Q000378:metabolism; D027981:Symporters; D014233:Tricarboxylic Acids / Q000494:pharmacology
D002352:Carrier Proteins; D018076:DNA, Complementary; D029382:Dicarboxylic Acid Transporters; D003998:Dicarboxylic Acids; D008565:Membrane Proteins; D029363:Organic Anion Transporters, Sodium-Dependent; D011994:Recombinant Proteins; C092524:SLC13A2 protein, human; C490478:Slc13a2 protein, rat; D013386:Succinates; D027981:Symporters; D014233:Tricarboxylic Acids