Universität zu Köln

Skwara, Peter, Schoemig, Edgar and Gruendemann, Dirk (2017). A novel mode of operation of SLC22A11: Membrane insertion of estrone sulfate versus translocation of uric acid and glutamate. Biochem. Pharmacol., 128. S. 74 - 83. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1873-2968

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Abstract

Estrone sulfate alias estrone-3-sulfate (E3S) is considerably larger and much more hydrophobic than typical substrates of SLC22 transporters. It is puzzling that many otherwise unrelated transporters have been reported to transport E3S. Here we scrutinized the mechanism of transport of E3S by SLC22A11 (alias OAT4), by direct comparison with uric acid (UA), an important physiological substrate. Heterologous expression of SLC22A11 in human 293 cells gave rise to a huge unidirectional efflux of glutamate (Glu) and aspartate, as determined by LC-MS/MS. The uptake of E3S was 20-fold faster than the uptake of UA. Yet, the outward transport of Glu was inhibited by extracellular E3S, but not by UA. The release of E3S after preloading was trans-stimulated by extracellular dehydroepiandrosterone sulfate (DHEAS), but neither by UA nor 6-carboxyfluorescein (6CF). The equilibrium accumulation of E3S was enhanced 3-fold by replacement of chloride with gluconate, but the opposite effect was observed for UA. These results establish that SLC22A11 provides entirely different transport mechanisms for E3S and UA. Therefore, E3S must not be used as a substitute for UA to assay the function of SLC22A11. In equilibrium accumulation experiments, the transporter-mediated uptake was a linear function of the concentration of UA and 6CF. By contrast, in the same concentration range the graph for E3S was hyperbolic. This suggests that SLC22A11 inserts E3S into a small volume with limited capacity, the plasma membrane. Our data support the notion that the reverse process, extraction from the membrane, is also catalyzed by the carrier. (C) 2017 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Skwara, Peter UNSPECIFIED UNSPECIFIED UNSPECIFIED Schoemig, Edgar UNSPECIFIED UNSPECIFIED UNSPECIFIED Gruendemann, Dirk UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-236572
DOI:	10.1016/j.bcp.2016.12.020
Journal or Publication Title:	Biochem. Pharmacol.
Volume:	128
Page Range:	S. 74 - 83
Date:	2017
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication:	OXFORD
ISSN:	1873-2968
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ORGANIC ANION TRANSPORTER; HUMAN CELL-LINES; MOLECULAR-IDENTIFICATION; SUBSTRATE-SPECIFICITY; PROTEIN EXPRESSION; URATE TRANSPORTER; BINDING; TAUROCHOLATE; REPLICATION; EXCRETION Multiple languages Pharmacology & Pharmacy Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23657