Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 278, Issue 25, Pages 22644-22649Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M212399200
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The mechanism for the cellular extrusion of sulfated conjugates is still unknown. In the present study, we investigated whether human wild type ABCG2 transports estrone 3-sulfate (E1S) using membrane vesicles from cDNA-transfected mouse lymphoma cell line (P388 cells). The uptake of [H-3]E1S into ABCG2-expressing membrane vesicles was stimulated by ATP, and the Km value for [H-3]E1S was determined to be 16.6 muM. The ABCG2-mediated transport of [H-3]E1S was potently inhibited by SN-38 and many sulfate conjugates but not by glucuronide and glutathione conjugates or other anionic compounds. Other sulfate conjugates such as [H-3] dehydroepiandrosterone sulfate (DHEAS) and [S-35]4-methylumbelliferone sulfate (K-m = 12.9 muM) and [S-35]6-hydroxy-5,7-dimethyl-2-methylamino-4-(3-pyridylmethyl) benzothiazole (E3040) sulfate (K-m = 26.9 muM) were also transported by ABCG2. Although [H-3]methotrexate, [H-3]17beta-estradiol-17beta-D-glucuronide, [H-3]2,4-dinitrophenyl-S-glutathione, and [C-14]4-methylumbelliferone glucuronide were transported by ABCG2, this took place to a much lesser extent compared with [H-3]E1S. It was suggested that ABCG2 preferentially transports sulfate conjugates and that E1S and DHEAS are the potential physiological substrates for this transporter.
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