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Cations Affect [ 3 H]Mazindol and [ 3 H]WIN 35,428 Binding to the Human Dopamine Transporter in a Similar Fashion
Author(s) -
Wu Qun,
Coffey Lori L.,
Reith Maarten E. A.
Publication year - 1997
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1997.69031106.x
Subject(s) - mazindol , dopamine transporter , chemistry , membrane , transporter , binding site , biophysics , dopamine plasma membrane transport proteins , dopamine , stereochemistry , biochemistry , biology , endocrinology , gene
The present study addresses the possibility that there are different cocaine‐related and mazindol‐related binding domains on the dopamine transporter (DAT) that show differential sensitivity to cations. The effects of Zn 2+ , Mg 2+ , Hg 2+ , Li + , K + , and Na + were assessed on the binding of [ 3 H]mazindol and [ 3 H]WIN 35,428 to the human (h) DAT expressed in C6 glioma cells under identical conditions for intact cell and membrane assays. The latter were performed at both 0 and 21°C. Zn 2+ (30–100 µ M ) stimulated binding of both radioligands to membranes, with a relatively smaller effect for [ 3 H]mazindol; Mg 2+ (0.1–100 µ M ) had no effect; Hg 2+ at ∼3 µ M stimulated binding to membranes, with a relatively smaller effect for [ 3 H]mazindol than [ 3 H]WIN 35,428 at 0°C, and at 30–100 µ M inhibited both intact cell and membrane binding; Li + and K + substitution (30–100 m M ) inhibited binding to membranes more severely than to intact cells; and Na + substitution was strongly stimulatory. With only a few exceptions, the patterns of ion effects were remarkably similar for both radioligands at both 0 and 21°C, suggesting the involvement of common binding domains on the hDAT impacted similarly by cations. Therefore, if there are different binding domains for WIN 35,428 and mazindol, these are not affected differentially by the cations studied in the present experiments, except for the stimulatory effect of Zn 2+ at 0 and 21°C and Hg 2+ at 0°C.