Stability study on renal type I mineralocorticoid receptor
The purpose of this work is to review stability and activation properties of type 1 receptor, in order to explain the reasons for its extreme in vitro instability. We demonstrate that the treatment of rat kidney cytosol with H2O2 prevents aldosterone binding, DNA/steroid- receptor complex interactio...
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00243205_v59_n7_p511_Galigniana |
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| Sumario: | The purpose of this work is to review stability and activation properties of type 1 receptor, in order to explain the reasons for its extreme in vitro instability. We demonstrate that the treatment of rat kidney cytosol with H2O2 prevents aldosterone binding, DNA/steroid- receptor complex interactions, and prevents the receptor thermal inactivation. In contrast, exogenous sulfhydryl reducing reagents are necessary to insure maximum binding of mineralocorticoid receptor and DNA/steroid-receptor interaction. However, the presence of β- mercaptoethanol in thermal induced incubations reverts the H2O2 protection. We also demonstrate that contaminations with free or sequestered iron are harmful for both, receptor binding capacity (in a reversible form) and for hormone-receptor/DNA binding properties (in a partially reversible form). We propose a sulfhydryl oxidative mechanism for type I mineralocorticoid receptor inactivation in which iron contaminants might accelerate this process by oxidative catalysis. We also demonstrate that when thiol groups are blocked by specific reagents such as N-ethyl-maleimide or dithionitrobenzoic acid, type I sites loose binding capacity, but the protein is protected from oxidation as well as inactivation. |
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