author_facet Pelis, Ryan M.
Dangprapai, Yodying
Wunz, Theresa M.
Wright, Stephen H.
Pelis, Ryan M.
Dangprapai, Yodying
Wunz, Theresa M.
Wright, Stephen H.
author Pelis, Ryan M.
Dangprapai, Yodying
Wunz, Theresa M.
Wright, Stephen H.
spellingShingle Pelis, Ryan M.
Dangprapai, Yodying
Wunz, Theresa M.
Wright, Stephen H.
American Journal of Physiology-Renal Physiology
Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
Physiology
author_sort pelis, ryan m.
spelling Pelis, Ryan M. Dangprapai, Yodying Wunz, Theresa M. Wright, Stephen H. 1931-857X 1522-1466 American Physiological Society Physiology http://dx.doi.org/10.1152/ajprenal.00496.2006 <jats:p>Human organic cation transporter 2 (hOCT2) is essential for the renal tubular secretion of many toxic organic cations. Previously, of the cysteines (C437, C451, C470, and C474) that occur within transmembrane helices that comprise the hydrophilic cleft (proposed site of substrate binding), only C474 was accessible to maleimide-PEO<jats:sub>2</jats:sub>-biotin (hydrophilic thiol-reactive reagent), and covalent modification of this residue caused lower transport rates (Pelis RM, Zhang X, Dangprapai Y, Wright SH, J Biol Chem 281: 35272–35280, 2006). Thus it was hypothesized that the environmental contaminant Hg<jats:sup>2+</jats:sup>(as HgCl<jats:sub>2</jats:sub>) would interact with C474 to reduce hOCT2-mediated transport. Uptake of [<jats:sup>3</jats:sup>H]tetraethylammonium (TEA) into Chinese hamster ovary cells stably expressing hOCT2 was reduced in a concentration-dependent manner by HgCl<jats:sub>2</jats:sub>, with an IC<jats:sub>50</jats:sub>of 3.9 ± 0.11 μM. Treatment with 10 μM HgCl<jats:sub>2</jats:sub>caused a sixfold reduction in the maximal rate of TEA transport but did not alter the affinity of hOCT2 for TEA. To determine which cysteines interact with Hg<jats:sup>2+</jats:sup>, a mutant with all four cleft cysteines converted to alanines (quadruple mutant), and four variants of this mutant, each with an individual cysteine restored, were created. The quadruple mutant was less sensitive to HgCl<jats:sub>2</jats:sub>than wild-type, whereas the C451- and C474-containing mutants were more sensitive than the quadruple mutant. Consistent with the HgCl<jats:sub>2</jats:sub>effect on transport, MTSEA-biotin only interacted with C451 and C474. These data indicate that C451 and C474 of hOCT2 reside in the aqueous milieu of the cleft and that interaction of Hg<jats:sup>2+</jats:sup>with these residues causes reduced TEA transport activity.</jats:p> Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity American Journal of Physiology-Renal Physiology
doi_str_mv 10.1152/ajprenal.00496.2006
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series American Journal of Physiology-Renal Physiology
source_id 49
title Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_unstemmed Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_full Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_fullStr Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_full_unstemmed Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_short Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_sort inorganic mercury interacts with cysteine residues (c451 and c474) of hoct2 to reduce its transport activity
topic Physiology
url http://dx.doi.org/10.1152/ajprenal.00496.2006
publishDate 2007
physical F1583-F1591
description <jats:p>Human organic cation transporter 2 (hOCT2) is essential for the renal tubular secretion of many toxic organic cations. Previously, of the cysteines (C437, C451, C470, and C474) that occur within transmembrane helices that comprise the hydrophilic cleft (proposed site of substrate binding), only C474 was accessible to maleimide-PEO<jats:sub>2</jats:sub>-biotin (hydrophilic thiol-reactive reagent), and covalent modification of this residue caused lower transport rates (Pelis RM, Zhang X, Dangprapai Y, Wright SH, J Biol Chem 281: 35272–35280, 2006). Thus it was hypothesized that the environmental contaminant Hg<jats:sup>2+</jats:sup>(as HgCl<jats:sub>2</jats:sub>) would interact with C474 to reduce hOCT2-mediated transport. Uptake of [<jats:sup>3</jats:sup>H]tetraethylammonium (TEA) into Chinese hamster ovary cells stably expressing hOCT2 was reduced in a concentration-dependent manner by HgCl<jats:sub>2</jats:sub>, with an IC<jats:sub>50</jats:sub>of 3.9 ± 0.11 μM. Treatment with 10 μM HgCl<jats:sub>2</jats:sub>caused a sixfold reduction in the maximal rate of TEA transport but did not alter the affinity of hOCT2 for TEA. To determine which cysteines interact with Hg<jats:sup>2+</jats:sup>, a mutant with all four cleft cysteines converted to alanines (quadruple mutant), and four variants of this mutant, each with an individual cysteine restored, were created. The quadruple mutant was less sensitive to HgCl<jats:sub>2</jats:sub>than wild-type, whereas the C451- and C474-containing mutants were more sensitive than the quadruple mutant. Consistent with the HgCl<jats:sub>2</jats:sub>effect on transport, MTSEA-biotin only interacted with C451 and C474. These data indicate that C451 and C474 of hOCT2 reside in the aqueous milieu of the cleft and that interaction of Hg<jats:sup>2+</jats:sup>with these residues causes reduced TEA transport activity.</jats:p>
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author Pelis, Ryan M., Dangprapai, Yodying, Wunz, Theresa M., Wright, Stephen H.
author_facet Pelis, Ryan M., Dangprapai, Yodying, Wunz, Theresa M., Wright, Stephen H., Pelis, Ryan M., Dangprapai, Yodying, Wunz, Theresa M., Wright, Stephen H.
author_sort pelis, ryan m.
container_issue 5
container_start_page 0
container_title American Journal of Physiology-Renal Physiology
container_volume 292
description <jats:p>Human organic cation transporter 2 (hOCT2) is essential for the renal tubular secretion of many toxic organic cations. Previously, of the cysteines (C437, C451, C470, and C474) that occur within transmembrane helices that comprise the hydrophilic cleft (proposed site of substrate binding), only C474 was accessible to maleimide-PEO<jats:sub>2</jats:sub>-biotin (hydrophilic thiol-reactive reagent), and covalent modification of this residue caused lower transport rates (Pelis RM, Zhang X, Dangprapai Y, Wright SH, J Biol Chem 281: 35272–35280, 2006). Thus it was hypothesized that the environmental contaminant Hg<jats:sup>2+</jats:sup>(as HgCl<jats:sub>2</jats:sub>) would interact with C474 to reduce hOCT2-mediated transport. Uptake of [<jats:sup>3</jats:sup>H]tetraethylammonium (TEA) into Chinese hamster ovary cells stably expressing hOCT2 was reduced in a concentration-dependent manner by HgCl<jats:sub>2</jats:sub>, with an IC<jats:sub>50</jats:sub>of 3.9 ± 0.11 μM. Treatment with 10 μM HgCl<jats:sub>2</jats:sub>caused a sixfold reduction in the maximal rate of TEA transport but did not alter the affinity of hOCT2 for TEA. To determine which cysteines interact with Hg<jats:sup>2+</jats:sup>, a mutant with all four cleft cysteines converted to alanines (quadruple mutant), and four variants of this mutant, each with an individual cysteine restored, were created. The quadruple mutant was less sensitive to HgCl<jats:sub>2</jats:sub>than wild-type, whereas the C451- and C474-containing mutants were more sensitive than the quadruple mutant. Consistent with the HgCl<jats:sub>2</jats:sub>effect on transport, MTSEA-biotin only interacted with C451 and C474. These data indicate that C451 and C474 of hOCT2 reside in the aqueous milieu of the cleft and that interaction of Hg<jats:sup>2+</jats:sup>with these residues causes reduced TEA transport activity.</jats:p>
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spelling Pelis, Ryan M. Dangprapai, Yodying Wunz, Theresa M. Wright, Stephen H. 1931-857X 1522-1466 American Physiological Society Physiology http://dx.doi.org/10.1152/ajprenal.00496.2006 <jats:p>Human organic cation transporter 2 (hOCT2) is essential for the renal tubular secretion of many toxic organic cations. Previously, of the cysteines (C437, C451, C470, and C474) that occur within transmembrane helices that comprise the hydrophilic cleft (proposed site of substrate binding), only C474 was accessible to maleimide-PEO<jats:sub>2</jats:sub>-biotin (hydrophilic thiol-reactive reagent), and covalent modification of this residue caused lower transport rates (Pelis RM, Zhang X, Dangprapai Y, Wright SH, J Biol Chem 281: 35272–35280, 2006). Thus it was hypothesized that the environmental contaminant Hg<jats:sup>2+</jats:sup>(as HgCl<jats:sub>2</jats:sub>) would interact with C474 to reduce hOCT2-mediated transport. Uptake of [<jats:sup>3</jats:sup>H]tetraethylammonium (TEA) into Chinese hamster ovary cells stably expressing hOCT2 was reduced in a concentration-dependent manner by HgCl<jats:sub>2</jats:sub>, with an IC<jats:sub>50</jats:sub>of 3.9 ± 0.11 μM. Treatment with 10 μM HgCl<jats:sub>2</jats:sub>caused a sixfold reduction in the maximal rate of TEA transport but did not alter the affinity of hOCT2 for TEA. To determine which cysteines interact with Hg<jats:sup>2+</jats:sup>, a mutant with all four cleft cysteines converted to alanines (quadruple mutant), and four variants of this mutant, each with an individual cysteine restored, were created. The quadruple mutant was less sensitive to HgCl<jats:sub>2</jats:sub>than wild-type, whereas the C451- and C474-containing mutants were more sensitive than the quadruple mutant. Consistent with the HgCl<jats:sub>2</jats:sub>effect on transport, MTSEA-biotin only interacted with C451 and C474. These data indicate that C451 and C474 of hOCT2 reside in the aqueous milieu of the cleft and that interaction of Hg<jats:sup>2+</jats:sup>with these residues causes reduced TEA transport activity.</jats:p> Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity American Journal of Physiology-Renal Physiology
spellingShingle Pelis, Ryan M., Dangprapai, Yodying, Wunz, Theresa M., Wright, Stephen H., American Journal of Physiology-Renal Physiology, Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity, Physiology
title Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_full Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_fullStr Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_full_unstemmed Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_short Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
title_sort inorganic mercury interacts with cysteine residues (c451 and c474) of hoct2 to reduce its transport activity
title_unstemmed Inorganic mercury interacts with cysteine residues (C451 and C474) of hOCT2 to reduce its transport activity
topic Physiology
url http://dx.doi.org/10.1152/ajprenal.00496.2006