A comparison of the inhibitory potency of reversibly acting inhibitors of anion transport on chloride and sulfate movements across the human red cell membrane |
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Authors: | Chuan-Pao Ku Michael L. Jennings Hermann Passow |
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Affiliation: | Department of Cell Physiology, Max-Planck Institut fur Biophysik, Frankfurt am Main, F.R.G. |
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Abstract: | The effects of a variety of chemically diverse, reversibly acting inhibitors have been measured on both Cl? and SO42? equilibrium exchange across the human red cell membrane. The measurements were carried out under the same conditions (pH 6.3, 8°C) and in the same medium for both the Cl? and SO24 tracer fluxes. Under these conditions the rate constant for Cl?-Cl? exchange is about 20 000 times larger than that for SO42?-SO42? exchange. Despite this large difference in the rates of transport of the two anions, eight different reversibly acting inhibitors have virtually the same effect on the Cl? and SO42? transport. The proteolytic enzyme papain also has the same inhibitory effect on both the Cl? and SO42? self-exchange. In addition, the slowly penetrating disulfonate 2-(4′-aminophenyl)-6-methylbenzenethiazol-3′,7-disulfonic acid (APMB) is 5-fold more effective from the outer than from the inner membrane surface in inhibiting both Cl? and SO42? self-exchange. We interpret these results as evidence that the rapidly penetrating monovalent anion Cl? and the slowly penetrating divalent anion SO42? are transported by the same system. |
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Keywords: | Anion transport Transport inhibition Sulfate transport Band 3 protein (Human red cell) ANS 1-analino-8-naphthalene sulfonic acid 4,4′-diisothiocyano dihydrostilbene-2,2′-disulfonic acid APMB 2-(4′-aminophenyl)-6-methylbenzenethiazol-3′,7-disulfonic acid DAS 4,4′-diacetamido stilbene-2,2′-disulfonic acid Hoechst B |
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