Inactivation of [125I]-angiotensin II binding sites in rat renal cortex epithelial membranes by dithiothreitol.


Preincubation of renal epithelial membranes with DTT produced a dose-dependent inhibition of specific [125I]-angiotensin binding, with an IC50 of 1 mM and total loss of binding at 5-10 mM DTT. Inactivation of specific [125I]-angiotensin II binding by DTT was temperature sensitive; the t1/2 at 22 degrees was 6 min compared with 30 min at 4 degrees. A rapid inactivation rate was dependent on the presence of NaCl. In the presence of 120 mM NaCl the t1/2 for inactivation by DTT was 6 min and 33 min in the absence of NaCl. Protection against DTT inactivation was obtained by preincubating membranes with unlabelled angiotensin II greater than angiotensin I greater than renin substrate while the dipeptide, Ileu-His was only effective in protecting the binding site at high concentrations (10 mM). Preincubations with DTT (1 mM) caused a 43% decrease in Bmax from 217.0 +/- 39.5 to 123.7 +/- 30.9 fmol bound/mg protein while the KD was not significantly affected.

Cite this paper

@article{Cox1984InactivationO, title={Inactivation of [125I]-angiotensin II binding sites in rat renal cortex epithelial membranes by dithiothreitol.}, author={H M Cox and Kenneth A. Munday and Judith A. Poat}, journal={Biochemical pharmacology}, year={1984}, volume={33 24}, pages={4057-62} }