Effect of chemical inactivating agents on glucocorticoid receptor proteins in mouse and hamster cells.

The ffect of N-ethylmaleimide and iodoacetamide on the glucocorticoid receptor activity extracted from the cytosol of either mouse of hamster cells has been investigated. Treatment of mouse or hamster cytosol with N-ethylmaleimide or iodoacetamide rapidly inactivates the [3H]glucocorticoid hormone binding activity of either cytosol. Prebinding the glucocorticoid hormone, dexamethasone, to the cytosol receptor blocks the rapid inactivation of the receptor by N-ethylmaleimide. Treatment of the prebound hormone-receptor complex with iodoacetamide prevents the subsequent binding of the hormone-receptor complex to DNA without causing a dissociation of the complex. Although the conclusions may be limited by the lack of purity of the receptor, the results suggest that a sulfhydryl group is involved in the binding of glucocorticoid hormones to the receptor protein. In addition, the results suggest that iodoacetamide is inactivating a separate chemical site which is necessary for the binding of the hormone-receptor complex to DNA.