| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
J. Biol. Chem., Vol. 278, Issue 6, 3705-3712, February 7, 2003
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
From the Department of Biochemistry, Hadassah Medical School,
Hebrew University, Jerusalem 91120, Israel
The sodium- and chloride-dependent
Transmembrane Domain I of the
-Aminobutyric Acid Transporter
GAT-1 Plays a Crucial Role in the Transition between Cation Leak and
Transport Modes*
-aminobutyric acid (GABA) transporter is essential for synaptic
transmission by this neurotransmitter. GAT-1 expressed in
Xenopus laevis oocytes exhibits
sodium-dependent GABA-induced inward currents reflecting
electrogenic sodium-coupled transport. In lithium-containing medium,
GAT-1 mediates GABA-independent currents, the relationship of which to
the physiological transport process is poorly understood. In this
study, mutants are described that appear to be locked in this cation
leak mode. When Gly63, located in the middle of the highly
conserved transmembrane domain I, was mutated to serine or
cysteine, sodium-dependent GABA currents were abolished.
Strikingly, these mutants exhibited robust inward currents in lithium-
as well as potassium-containing media. Membrane-impermeant sulfhydryl
reagents inhibited these currents of the cysteine but not of the serine
mutant, indicating that this position was accessible to the external
aqueous medium. The cation leak currents mediated by wild-type
GAT-1 were inhibited by low millimolar sodium concentrations in a
noncompetitive manner. Mutations at other positions of transmembrane
domain I increased or decreased the apparent sodium affinity, as
monitored by the sodium-dependent steady-state GABA
currents or transient currents. In parallel, the ability of
sodium to inhibit the cation leak currents was increased or decreased,
respectively. Thus, transmembrane domain I of GAT-1 contains
determinants controlling both sodium-coupled GABA flux and the cation
leak pathway as well as the interconversion of these distinct modes.
Our observations suggest the possibility that the permeation pathway in
both modes shares common structural elements.
*
This work was supported by Israel Science Foundation Grant
150/00-16.1, by the Federal Ministry of Education, Science, Research, and Technology of Germany and its International Bureau at the Deutsches
Zentrum für Luft und Raumfahrt, and by the Bernard Katz Minerva
Center for Cellular Biophysics.The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement" in accordance with 18 U.S.C. Section
1734 solely to indicate this fact.
To whom correspondence should be addressed: Dept. of Biochemistry,
Hadassah Medical School, Hebrew University, P. O. Box 12272, Jerusalem
91120, Israel. Tel.: 972-2-675-8506; Fax: 972-2-675-7379; E-mail:
kannerb@cc.huji.ac.il.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  A. Rosenberg and B. I. Kanner The Substrates of the {gamma}-Aminobutyric Acid Transporter GAT-1 Induce Structural Rearrangements around the Interface of Transmembrane Domains 1 and 6 J. Biol. Chem., May 23, 2008; 283(21): 14376 - 14383. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Dodd and D. L. Christie Selective Amino Acid Substitutions Convert the Creatine Transporter to a {gamma}-Aminobutyric Acid Transporter J. Biol. Chem., May 25, 2007; 282(21): 15528 - 15533. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Zhou, E. Zomot, and B. I. Kanner Identification of a Lithium Interaction Site in the {gamma}-Aminobutyric Acid (GABA) Transporter GAT-1 J. Biol. Chem., August 4, 2006; 281(31): 22092 - 22099. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Zomot, Y. Zhou, and B. I. Kanner Proximity of Transmembrane Domains 1 and 3 of the {gamma}-Aminobutyric Acid Transporter GAT-1 Inferred from Paired Cysteine Mutagenesis J. Biol. Chem., July 8, 2005; 280(27): 25512 - 25516. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Zhou and B. I. Kanner Transporter-associated Currents in the {gamma}-Aminobutyric Acid Transporter GAT-1 Are Conditionally Impaired by Mutations of a Conserved Glycine Residue J. Biol. Chem., May 27, 2005; 280(21): 20316 - 20324. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A.-K. Meinild, H. H. Sitte, and U. Gether Zinc Potentiates an Uncoupled Anion Conductance Associated with the Dopamine Transporter J. Biol. Chem., November 26, 2004; 279(48): 49671 - 49679. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Melamed and B. I. Kanner Transmembrane Domains I and II of the {gamma}-Aminobutyric Acid Transporter GAT-4 Contain Molecular Determinants of Substrate Specificity Mol. Pharmacol., June 1, 2004; 65(6): 1452 - 1461. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Zhou, E. R. Bennett, and B. I. Kanner The Aqueous Accessibility in the External Half of Transmembrane Domain I of the GABA Transporter GAT-1 Is Modulated by Its Ligands J. Biol. Chem., April 2, 2004; 279(14): 13800 - 13808. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. K. Henry, E. M. Adkins, Q. Han, and R. D. Blakely Serotonin and Cocaine-sensitive Inactivation of Human Serotonin Transporters by Methanethiosulfonates Targeted to Transmembrane Domain I J. Biol. Chem., September 26, 2003; 278(39): 37052 - 37063. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. F. Sacchi, M. Castagna, S. A. Mari, C. Perego, E. Bossi, and A. Peres Glutamate 59 is critical for transport function of the amino acid cotransporter KAAT1 Am J Physiol Cell Physiol, September 1, 2003; 285(3): C623 - C632. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| All ASBMB Journals | Molecular and Cellular Proteomics |
| Journal of Lipid Research | ASBMB Today |
