Enzymes
| UniProtKB help_outline | 644 proteins |
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- Name help_outline dehydroepiandrosterone 3-sulfate Identifier CHEBI:57905 (Beilstein: 3916013) help_outline Charge -1 Formula C19H27O5S InChIKeyhelp_outline CZWCKYRVOZZJNM-USOAJAOKSA-M SMILEShelp_outline C1[C@@]2([C@@]([C@@]3(C(C[C@@H](OS([O-])(=O)=O)CC3)=C1)C)(CC[C@]4([C@]2(CCC4=O)[H])C)[H])[H] 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 H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,932 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:75487 | RHEA:75488 | RHEA:75489 | RHEA:75490 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
| UniProtKB help_outline |
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Publications
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Functional characterization of pH-sensitive organic anion transporting polypeptide OATP-B in human.
Nozawa T., Imai K., Nezu J., Tsuji A., Tamai I.
The pH-sensitive activity of human organic anion transporting polypeptide OATP-B, which is expressed at the apical membrane of human small intestinal epithelial cells, was functionally characterized. When initial uptake of estrone-3-sulfate, a typical substrate of OATP, was studied kinetically, we ... >> More
The pH-sensitive activity of human organic anion transporting polypeptide OATP-B, which is expressed at the apical membrane of human small intestinal epithelial cells, was functionally characterized. When initial uptake of estrone-3-sulfate, a typical substrate of OATP, was studied kinetically, we observed an increase in V(max) with decrease of pH from 7.4 to 5.0, whereas the change in K(m) was negligible. OATP-B-mediated uptake of estrone-3-sulfate was independent of sodium, chloride, bicarbonate, or glutathione, whereas the proton ionophore carbonylcyanide p-trifluoromethoxyphenylhydrazone exhibited a pH-dependent inhibitory effect, suggesting that a proton gradient is a driving force for OATP-B. When OATP-B was expressed in human embryonic kidney 293 cells, uptake activities for anionic compounds showed various kinds of pH sensitivity. Dehydroepiandrosterone-sulfate, estrone-3-sulfate, and fexofenadine were transported by OATP-B at both neutral and acidic pH, whereas estradiol-17beta-glucuronide, acetic acid, and lactic acid were not transported at all. Transport of taurocholic acid and pravastatin by OATP-B was observed only at acidic pH, demonstrating a pH-sensitive substrate specificity of OATP-B. Because the physiological pH close to the surface of intestinal epithelial cells is acidic, the roles of OATP-B in the small intestine might be different from those in other tissues, such as liver basolateral membrane. Although the driving force for OATP-B has not been fully established, the clarification of factors, such as pH, that affect the OATP-B-activity is essential for an understanding of the physiological and pharmacological relevance of the transporter in the small intestine. << Less
J. Pharmacol. Exp. Ther. 308:438-445(2004) [PubMed] [EuropePMC]