HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 539/1/3    most recent 2001.013303v2 2001.013303v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bröer, A. Articles by Bröer, S. Search for Related Content PubMed PubMed Citation Articles by Bröer, A. Articles by Bröer, S.

Regulation of the glutamine transporter SN1 by extracellular pH and intracellular sodium ions

Angelika Bröer, Alexandra Albers *, Iwan Setiawan *, Robert H. Edwards †, Farrukh A. Chaudhry †, Florian Lang *, Carsten A. Wagner § and Stefan Bröer

The glutamine transporter SN1 has recently been identified as one of the major glutamine transporters in hepatocytes and brain astrocytes. It appears to be the molecular correlate of system N amino acid transport. Two different transport mechanisms have been proposed for this transporter. These are an electroneutral mechanism, in which glutamine uptake is coupled to an exchange of 1Na⁺ and 1H⁺, or an electrogenic mechanism coupled to the exchange of 2Na⁺ against 1H⁺. This study was performed to solve these discrepancies and to investigate the reversibility of the transporter. When SN1 was expressed in Xenopus laevis oocytes, glutamine uptake was accompanied by a cotransport of 2-3 Na⁺ ions as determined by ²²Na⁺ fluxes. However, at the same time a rapid release of intracellular Na⁺ was observed indicating an active exchange of Na⁺ ions. The driving force of the proton electrochemical gradient was equivalent to that of the sodium electrochemical gradient. Acidification of the extracellular medium caused the transporter to run in reverse and to release glutamine. Determination of accumulation ratios at different driving forces were in agreement with an electroneutral 1Na⁺-glutamine cotransport-1H⁺ antiport. Inward currents that were observed during glutamine uptake were much smaller than expected for a stoichiometric cotransport of charges. A slippage mode in the transporter mechanism and pH-regulated endogenous oocyte cation channels are likely to contribute to the observed currents.

This article has been cited by other articles:

				S. Broer Amino Acid Transport Across Mammalian Intestinal and Renal Epithelia Physiol Rev, January 1, 2008; 88(1): 249 - 286. [Abstract] [Full Text] [PDF]

				A. Weise, H. M. Becker, and J. W. Deitmer Enzymatic Suppression of the Membrane Conductance Associated with the Glutamine Transporter SNAT3 Expressed in Xenopus Oocytes by Carbonic Anhydrase II J. Gen. Physiol., July 30, 2007; 130(2): 203 - 215. [Abstract] [Full Text] [PDF]

				H.-P. Schneider, S. Broer, A. Broer, and J. W. Deitmer Heterologous Expression of the Glutamine Transporter SNAT3 in Xenopus Oocytes Is Associated with Four Modes of Uncoupled Transport J. Biol. Chem., February 9, 2007; 282(6): 3788 - 3798. [Abstract] [Full Text] [PDF]

				C. Moret, M. H. Dave, N. Schulz, J. X. Jiang, F. Verrey, and C. A. Wagner Regulation of renal amino acid transporters during metabolic acidosis Am J Physiol Renal Physiol, February 1, 2007; 292(2): F555 - F566. [Abstract] [Full Text] [PDF]

				F. E. Baird, K. J. Beattie, A. R. Hyde, V. Ganapathy, M. J. Rennie, and P. M. Taylor Bidirectional substrate fluxes through the System N (SNAT5) glutamine transporter may determine net glutamine flux in rat liver J. Physiol., September 1, 2004; 559(2): 367 - 381. [Abstract] [Full Text] [PDF]

				C. Grewer and E. Grabsch New inhibitors for the neutral amino acid transporter ASCT2 reveal its Na+-dependent anion leak J. Physiol., June 15, 2004; 557(3): 747 - 759. [Abstract] [Full Text] [PDF]

				A. Broer, K. Klingel, S. Kowalczuk, J. E. J. Rasko, J. Cavanaugh, and S. Broer Molecular Cloning of Mouse Amino Acid Transport System B0, a Neutral Amino Acid Transporter Related to Hartnup Disorder J. Biol. Chem., June 4, 2004; 279(23): 24467 - 24476. [Abstract] [Full Text] [PDF]

				P. Ala-Laurila, K. Donner, and A. Koskelainen Thermal Activation and Photoactivation of Visual Pigments Biophys. J., June 1, 2004; 86(6): 3653 - 3662. [Abstract] [Full Text] [PDF]

				B. Mackenzie, M. K.-H. Schafer, J. D. Erickson, M. A. Hediger, E. Weihe, and H. Varoqui Functional Properties and Cellular Distribution of the System A Glutamine Transporter SNAT1 Support Specialized Roles in Central Neurons J. Biol. Chem., June 20, 2003; 278(26): 23720 - 23730. [Abstract] [Full Text] [PDF]

				G. E. Mann, D. L. Yudilevich, and L. Sobrevia Regulation of Amino Acid and Glucose Transporters in Endothelial and Smooth Muscle Cells Physiol Rev, January 1, 2003; 83(1): 183 - 252. [Abstract] [Full Text] [PDF]

				F. A. Chaudhry, R. J. Reimer, and R. H. Edwards The glutamine commute: take the N line and transfer to the A J. Cell Biol., April 29, 2002; 157(3): 349 - 355. [Abstract] [Full Text] [PDF]

				F. A. Chaudhry, R. J. Reimer, and R. H. Edwards The glutamine commute: take the N line and transfer to the A J. Cell Biol., April 29, 2002; 157(3): 349 - 355. [Abstract] [Full Text] [PDF]