RGD Reference Report - Regulation of the glutamine transporter SN1 by extracellular pH and intracellular sodium ions. - Rat Genome Database

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

Authors: Bröer, Angelika  Albers, Alexandra  Setiawan, Iwan  Edwards, Robert H  Chaudhry, Farrukh A  Lang, Florian  Wagner, Carsten A  Bröer, Stefan 
Citation: Bröer A, etal., J Physiol. 2002 Feb 15;539(Pt 1):3-14. doi: 10.1113/jphysiol.2001.013303.
RGD ID: 152995544
Pubmed: PMID:11850497   (View Abstract at PubMed)
PMCID: PMC2290136   (View Article at PubMed Central)
DOI: DOI:10.1113/jphysiol.2001.013303   (Journal Full-text)

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.

Gene Ontology Annotations    

Biological Process

Molecular Function

Objects Annotated

Genes (Rattus norvegicus)
Slc38a3  (solute carrier family 38, member 3)

Additional Information