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Anion exchanger is present in both luminal and basolateral renal membranes
- Source :
- European Journal of Biochemistry. 164:695-702
- Publication Year :
- 1987
- Publisher :
- Wiley, 1987.
-
Abstract
- Binding of the anion-exchange inhibitor 3H2-labeled 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid (DIDS) to highly purified luminal and basolateral beef kidney tubular membranes was characterized. Specific binding of [3H2]DIDS is present in both luminal and basolateral membranes. Scatchard analysis revealed a Kd for [3H2]DIDS of 5.5 microM and 19.3 microM and a maximal number of binding sites of 10.9 nmol and 31.7 nmol DIDS/mg protein in basolateral and luminal membranes, respectively. To assess the role of this putative anion exchanger on transport we measured 35SO4 uptake by luminal and basolateral membranes. In both luminal and basolateral membranes sulfate uptake was significantly greater in the presence of an outward-directed Cl gradient, OH gradient or HCO3 gradient than in the absence of these gradients. There was an early anion-dependent sulfate uptake of five to ten times the equilibrium uptake at 60 min. The sulfate taken in could be released by lysis of the vesicles indicating true uptake and not binding of sulfate. No significant difference in SO4 uptake was found in the presence and in the absence of valinomycin, indicating that the anion exchanger is electroneutral. The anion-dependent sulfate uptake was completely inhibited by either DIDS or furosemide in both luminal and basolateral membranes. Dixon analysis of HCO3-dependent SO4 uptake by luminal membranes in the presence of different concentrations of DIDS revealed a Ki for DIDS of 20 microM. The similar values of the Kd for [3H2]DIDS binding and the Ki for DIDS inhibition of SO4 uptake might suggest an association between DIDS binding and the inhibition of SO4 transport. In addition, an inward-directed Na gradient stimulated sulfate uptake in luminal but not in basolateral membranes. The Na-dependent sulfate uptake in luminal membranes was also inhibited by DIDS. We conclude that, in addition to the well-known Na-dependent sulfate uptake in luminal membranes, there exists an anion exchanger in both basolateral and luminal membranes capable of sulfate transport.
- Subjects :
- 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid
Anion Transport Proteins
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
Biochemistry
chemistry.chemical_compound
Valinomycin
Chlorides
Stilbenes
Hydroxides
Animals
Binding site
Sulfate
Binding Sites
Sulfates
Vesicle
Membrane Proteins
Biological Transport
Sulfate transport
Transport protein
Bicarbonates
Kidney Tubules
Membrane
chemistry
DIDS
Cattle
Carrier Proteins
Subjects
Details
- ISSN :
- 14321033 and 00142956
- Volume :
- 164
- Database :
- OpenAIRE
- Journal :
- European Journal of Biochemistry
- Accession number :
- edsair.doi.dedup.....13688189ab57460e9f60a154c2d72658