Enzymes
| UniProtKB help_outline | 396 proteins |
Reaction participants Show >> << Hide
- Name help_outline orotate Identifier CHEBI:30839 (Beilstein: 3651747; CAS: 73-97-2) help_outline Charge -1 Formula C5H3N2O4 InChIKeyhelp_outline PXQPEWDEAKTCGB-UHFFFAOYSA-M SMILEShelp_outline [O-]C(=O)c1cc(=O)[nH]c(=O)[nH]1 2D coordinates Mol file for the small molecule Search links Involved in 14 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline L-glutamate Identifier CHEBI:29985 (CAS: 11070-68-1) help_outline Charge -1 Formula C5H8NO4 InChIKeyhelp_outline WHUUTDBJXJRKMK-VKHMYHEASA-M SMILEShelp_outline [NH3+][C@@H](CCC([O-])=O)C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 249 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:72043 | RHEA:72044 | RHEA:72045 | RHEA:72046 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Related reactions help_outline
More general form(s) of this reaction
Publications
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OAT2 catalyses efflux of glutamate and uptake of orotic acid.
Fork C., Bauer T., Golz S., Geerts A., Weiland J., Del Turco D., Schoemig E., Gruendemann D.
OAT (organic anion transporter) 2 [human gene symbol SLC22A7 (SLC is solute carrier)] is a member of the SLC22 family of transport proteins. In the rat, the principal site of expression of OAT2 is the sinusoidal membrane domain of hepatocytes. The particular physiological function of OAT2 in liver ... >> More
OAT (organic anion transporter) 2 [human gene symbol SLC22A7 (SLC is solute carrier)] is a member of the SLC22 family of transport proteins. In the rat, the principal site of expression of OAT2 is the sinusoidal membrane domain of hepatocytes. The particular physiological function of OAT2 in liver has been unresolved so far. In the present paper, we have used the strategy of LC (liquid chromatography)-MS difference shading to search for specific and cross-species substrates of OAT2. Heterologous expression of human and rat OAT2 in HEK (human embryonic kidney)-293 cells stimulated accumulation of the zwitterion trigonelline; subsequently, orotic acid was identified as an excellent and specific substrate of OAT2 from the rat (clearance=106 μl·min⁻¹·mg of protein⁻¹) and human (46 μl·min⁻¹·mg of protein⁻¹). The force driving uptake of orotic acid was identified as glutamate antiport. Efficient transport of glutamate by OAT2 was directly demonstrated by uptake of [³H]glutamate. However, because of high intracellular glutamate, OAT2 operates as glutamate efflux transporter. Thus expression of OAT2 markedly increased the release of glutamate (measured by LC-MS) from cells, even without extracellular exchange substrate. Orotic acid strongly trans-stimulated efflux of glutamate. We thus propose that OAT2 physiologically functions as glutamate efflux transporter. OAT2 mRNA was detected, after laser capture microdissection of rat liver slices, equally in periportal and pericentral regions; previous reports of hepatic release of glutamate into blood can now be explained by OAT2 activity. A specific OAT2 inhibitor could, by lowering plasma glutamate and thus promoting brain-to-blood efflux of glutamate, alleviate glutamate exotoxicity in acute brain conditions. << Less