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Regulation of Arsenic Triglutathione [As(GS) 3 ] Transport by the Human Multidrug Resistance Protein 1 (MRP1/ABCC1) Through Post‐translational Modification
Author(s) -
Shukalek Caley,
Conseil Gwenaelle,
Cole Susan PC,
Leslie Elaine M
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb502
Subject(s) - hela , biochemistry , cell culture , vesicle , chemistry , transfection , hek 293 cells , cell , biology , membrane , gene , genetics
The 190‐kDa ATP‐binding cassette transporter, MRP1, is responsible for exporting a diverse array of substrates from the cell including glutathione conjugates. Arsenic, a high priority environmental carcinogen and clinical anti‐cancer agent, is a substrate of MRP1 in its trigluathione form [As(GS) 3 ]. We initially characterized As(GS) 3 transport by MRP1 using membrane vesicles isolated from a doxorubicin‐selected small cell lung cancer cell line (H69AR) and found it to be a high apparent affinity substrate (K m 0.3 μM). In the current study, we show that the K m of MRP1 for As(GS) 3 depends upon the cell line it is expressed in. Thus, wild‐type MRP1‐enriched membrane vesicles exhibit a >10‐fold difference in K m for As(GS) 3 (0.3 μM vs 4.4 μM) when prepared from transfected HeLa vs HEK293 cells, respectively. On the other hand, mutant MRP1 lacking all N‐linked glycosylation (sugar‐free) expressed in either cell line exhibits a low K m (0.3 – 0.6 μM). Furthermore, when prepared in the presence of phosphatase inhibitors, both wild‐type and sugar‐free MRP1‐enriched membrane vesicles from either HeLa or HEK293 cells exhibit a high K m for As(GS) 3 (3 – 6 μM). Together, these results suggest that the affinity of MRP1 for As(GS) 3 is influenced by cell type, phosphorylation, and glycosylation and elucidate potential implications for the relative detoxification of arsenic by different cell types and tissues.