Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Bidirectional substrate fluxes through the system N (SNAT5) glutamine transporter may determine net glutamine flux in rat liver.
Baird FE
,
Beattie KJ
,
Hyde AR
,
Ganapathy V
,
Rennie MJ
,
Taylor PM
.
???displayArticle.abstract???
System N (SNAT3 and SNAT5) amino acid transporters are key mediators of glutamine transport across the plasma membrane of mammalian cell types, including hepatocytes and astrocytes. We demonstrate that SNAT5 shows simultaneous bidirectional glutamine fluxes when overexpressed in Xenopus oocytes. Influx and efflux are both apparently Na+ dependent but, since they are not directly coupled, the carrier is capable of mediating net amino acid movement across the cell membrane. The apparent Km values for glutamine influx and efflux are similar (approximately 1 mm) and the transporter behaviour is consistent with a kinetic model in which re-orientation of the carrier from outside- to inside-facing conformations (either empty or substrate loaded) is the limiting step in the transport cycle. In perfused rat liver, the observed relationship between influent (portal) glutamine concentration and net hepatic glutamine flux may be described by a simple kinetic model, assuming the balance between influx and efflux through System N determines net flux, where under physiological conditions efflux is generally saturated owing to high intracellular glutamine concentration. SNAT5 shows a more periportal mRNA distribution than SNAT3 in rat liver, indicating that SNAT5 may have particular importance for modulation of net hepatic glutamine flux.
Almond,
Hepatic glutamine metabolism and acid-base regulation.
1992, Pubmed
Almond,
Hepatic glutamine metabolism and acid-base regulation.
1992,
Pubmed
Babu,
Identification of a novel system L amino acid transporter structurally distinct from heterodimeric amino acid transporters.
2003,
Pubmed
,
Xenbase
Bode,
Recent molecular advances in mammalian glutamine transport.
2001,
Pubmed
Bröer,
Transfer of glutamine between astrocytes and neurons.
2001,
Pubmed
Bröer,
Regulation of the glutamine transporter SN1 by extracellular pH and intracellular sodium ions.
2002,
Pubmed
,
Xenbase
Chaudhry,
The glutamine commute: take the N line and transfer to the A.
2002,
Pubmed
Chaudhry,
Coupled and uncoupled proton movement by amino acid transport system N.
2001,
Pubmed
,
Xenbase
Chaudhry,
Glutamine uptake by neurons: interaction of protons with system a transporters.
2002,
Pubmed
Chaudhry,
Molecular analysis of system N suggests novel physiological roles in nitrogen metabolism and synaptic transmission.
1999,
Pubmed
Christie,
Intracellular sensing of amino acids in Xenopus laevis oocytes stimulates p70 S6 kinase in a target of rapamycin-dependent manner.
2002,
Pubmed
,
Xenbase
Costa,
Determination of ionic permeability coefficients of the plasma membrane of Xenopus laevis oocytes under voltage clamp.
1989,
Pubmed
,
Xenbase
Deitmer,
Glutamine efflux from astrocytes is mediated by multiple pathways.
2003,
Pubmed
,
Xenbase
Fafournoux,
Bidirectional transport of glutamine across the cell membrane in rat liver.
1983,
Pubmed
Fei,
Primary structure, genomic organization, and functional and electrogenic characteristics of human system N 1, a Na+- and H+-coupled glutamine transporter.
2000,
Pubmed
,
Xenbase
Gu,
Identification and characterization of an amino acid transporter expressed differentially in liver.
2000,
Pubmed
,
Xenbase
Haüssinger,
Nitrogen metabolism in liver: structural and functional organization and physiological relevance.
1990,
Pubmed
Häussinger,
Regulation of flux through glutaminase and glutamine synthetase in isolated perfused rat liver.
1983,
Pubmed
Häussinger,
Hepatic glutamine transport and metabolism.
1998,
Pubmed
Häussinger,
Role of plasma membrane transport in hepatic glutamine metabolism.
1985,
Pubmed
Kilberg,
Characteristics of an amino acid transport system in rat liver for glutamine, asparagine, histidine, and closely related analogs.
1980,
Pubmed
Lenzen,
pH control of hepatic glutamine degradation. Role of transport.
1987,
Pubmed
Low,
A quantitative analysis of the control of glutamine catabolism in rat liver cells. Use of selective inhibitors.
1993,
Pubmed
Low,
Substrate-specificity of glutamine transporters in membrane vesicles from rat liver and skeletal muscle investigated using amino acid analogues.
1991,
Pubmed
Low,
Transport of L-glutamine and L-glutamate across sinusoidal membranes of rat liver. Effects of starvation, diabetes and corticosteroid treatment.
1992,
Pubmed
Mackenzie,
Sodium-coupled neutral amino acid (System N/A) transporters of the SLC38 gene family.
2004,
Pubmed
Meier,
Activation of system L heterodimeric amino acid exchangers by intracellular substrates.
2002,
Pubmed
,
Xenbase
Nakanishi,
Structure, function, and tissue expression pattern of human SN2, a subtype of the amino acid transport system N.
2001,
Pubmed
Nakanishi,
Cloning and functional characterization of a new subtype of the amino acid transport system N.
2001,
Pubmed
,
Xenbase
Pardridge,
Unidirectional influx of glutamine and other neutral amino acids into liver of fed and fasted rat in vivo.
1977,
Pubmed
Peter,
Multiple components of arginine and phenylalanine transport induced in neutral and basic amino acid transporter-cRNA-injected Xenopus oocytes.
1996,
Pubmed
,
Xenbase
Peter,
Interactions between the thiol-group reagent N-ethylmaleimide and neutral and basic amino acid transporter-related amino acid transport.
1999,
Pubmed
,
Xenbase
Rahman,
Helix 8 and helix 10 are involved in substrate recognition in the rat monocarboxylate transporter MCT1.
1999,
Pubmed
,
Xenbase
Reimer,
Amino acid transport system A resembles system N in sequence but differs in mechanism.
2000,
Pubmed
Sano,
Isolation of a rat histidase cDNA sequence and expression in Escherichia coli--evidence of extrahepatic/epidermal distribution.
1997,
Pubmed
Sugawara,
Cloning of an amino acid transporter with functional characteristics and tissue expression pattern identical to that of system A.
2000,
Pubmed
,
Xenbase
Sugawara,
Structure and function of ATA3, a new subtype of amino acid transport system A, primarily expressed in the liver and skeletal muscle.
2000,
Pubmed
,
Xenbase
Taylor,
Amino-acid-dependent modulation of amino acid transport in Xenopus laevis oocytes.
1996,
Pubmed
,
Xenbase
Taylor,
Perivenous localisation of Na-dependent glutamate transport in perfused rat liver.
1987,
Pubmed
Varoqui,
Cloning and functional identification of a neuronal glutamine transporter.
2000,
Pubmed
Verleysdonk,
Synthesis and release of L-serine by rat astroglia-rich primary cultures.
2000,
Pubmed
Watford,
Glutamine and glutamate metabolism across the liver sinusoid.
2000,
Pubmed
Xiang,
Glutamine transport at the blood-brain and blood-cerebrospinal fluid barriers.
2003,
Pubmed
Yao,
A novel system A isoform mediating Na+/neutral amino acid cotransport.
2000,
Pubmed
,
Xenbase
Yudilevich,
Unidirectional uptake of substrates at the blood side of secretory epithelia: stomach, salivary gland, pancreas.
1982,
Pubmed