Intranuclear distribution of rat liver glucocorticoid receptors by nuclease digestion in a cell-free system

Intranuclear distribution of rat liver glucocorticoid receptors was examined. When the [3H]TA-receptor complex-bound nuclei were digested with micrococcal nuclease, the [3H]TA-receptor complex sedimented coincident with mono-, di- and trinucleosomes on a glycerol gradient. The specific activity of the [3H]TA-receptor associated with chromatin fragments in the Mg-soluble fraction was 13-fold higher than that in the Mg-insoluble fraction. In adrenalectomized rats, the nucleosome-bound [3H]TA-receptor complex was reduced, but the specific activity in the Mg-soluble fraction was almost the same as that in intact rats. Endogenous glucocorticoid receptor complex associated with mono-nucleosomes decreased 2 weeks after adrenalectomy. These results suggest that interaction between the glucocorticoid receptor complex and chromatin acceptor sites in intact and adrenalectomized rats occurred in the transcriptionally active chromatin regions which are sensitive to micrococcal nuclease.