|
|
||||||||
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston, Texas 77555-0641
The transport properties of the human
Na+-dicarboxylate cotransporter, (hNaDC-1), expressed in
Xenopus laevis oocytes were characterized using the
two-electrode voltage clamp technique. Steady-state succinate-evoked
inward currents in hNaDC-1 were dependent on the concentrations of
succinate and sodium, and on the membrane potential. At
50 mV, the
half-saturation constant for succinate
(K0.5succinate) was 1.1 mM and the
half-saturation constant for sodium
(K0.5sodium) was 65 mM. The Hill coefficient
was 2.3, which is consistent with a transport stoichiometry of 3 Na+:1 divalent anion substrate. The hNaDC-1 exhibits a
high-cation selectivity. Sodium is the preferred cation and other
cations, such as lithium, were not able to support transport of
succinate. The preferred substrates of hNaDC-1 are fumarate
(K0.5 1.8 mM) and succinate, followed by
methylsuccinate (K0.5 2.8 mM), citrate (K0.5 6.8 mM) and
-ketoglutarate
(K0.5 16 mM). The hNaDC-1 may also
transport sodium ions through an uncoupled leak pathway, which is
sensitive to phloretin inhibition. We propose a transport model for
hNaDC-1 in which the binding of three sodium ions is followed by
substrate binding.
sodium; succinate; Xenopus laevis oocytes; electrogenic cotransport
This article has been cited by other articles:
![]() |
A. M. Pajor and K. M. Randolph Inhibition of the Na+/Dicarboxylate Cotransporter by Anthranilic Acid Derivatives Mol. Pharmacol., November 1, 2007; 72(5): 1330 - 1336. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Oshiro and A. M. Pajor Functional characterization of high-affinity Na+/dicarboxylate cotransporter found in Xenopus laevis kidney and heart Am J Physiol Cell Physiol, November 1, 2005; 289(5): C1159 - C1168. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. M. Pajor and K. M. Randolph Conformationally Sensitive Residues in Extracellular Loop 5 of the Na+/Dicarboxylate Co-transporter J. Biol. Chem., May 13, 2005; 280(19): 18728 - 18735. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. C. Burckhardt, J. Lorenz, C. Kobbe, and G. Burckhardt Substrate specificity of the human renal sodium dicarboxylate cotransporter, hNaDC-3, under voltage-clamp conditions Am J Physiol Renal Physiol, April 1, 2005; 288(4): F792 - F799. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. M. Pajor, R. Gangula, and X. Yao Cloning and functional characterization of a high-affinity Na+/dicarboxylate cotransporter from mouse brain Am J Physiol Cell Physiol, May 1, 2001; 280(5): C1215 - C1223. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. M. Pajor Conformationally Sensitive Residues in Transmembrane Domain 9 of the Na+/dicarboxylate Co-transporter J. Biol. Chem., August 3, 2001; 276(32): 29961 - 29968. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |