Pavlik EJ, Katzenellenbogen BS. The intranuclear distribution of rat uterine estrogen receptors determined after nuclease treatment and chromatin fractionation.
Mol Cell Endocrinol 1982;
26:201-16. [PMID:
7084560 DOI:
10.1016/0303-7207(82)90017-x]
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Abstract
The intranuclear locations at which rat uterine estrogen receptors interact with chromatin have been probed using digestions performed with DNAase I and micrococcal nuclease. Exposure to nuclease has been controlled to effect limited to extensive digestion of nuclear DNA under conditions which maintain the integrity of the [3H] estradiol-receptor complex. The effect of divalent cation concentration on the release of estrogen receptors fron nuclease-treated chromatin was examined and found to be of consequence above 2 mM. Exposure to nuclease released nuclear estrogen receptors from chromatin, with DNAase I being more efficient than micrococcal nuclease in mediating this release. The release of the bulk of nuclear estrogen receptors closely paralleled the nuclease-mediated digestion of chromatin DNA. At 1 h after exposure to estrogen, substantial quantities of uterine estrogen receptors (80-90%) were distributed in chromatin fractions which, on the basis of fractionation terminology, have been termed 'transcriptionally inactive' by convention. Enrichment of estrogen receptors in chromatin which has been termed ' transcriptionally active' only occurred with 10-20% of the estrogen receptors. Hence, our findings support a model where, at early times after estrogen exposure, receptors from the rat uterus are enriched to only a minor extent in chromatin to which 'transcriptional activity' is generally assigned while the bulk of receptors are localized in chromatin which is generally considered 'transcriptionally inactive'.
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