Isolation of a chromatin fraction from calf endometrium highly enriched in estradiol binding sites.
The intranuclear distribution of [3H]-estradiol binding sites was studied in highly purified nuclei isolated from calf endometrial tissue pre-incubated with the labeled hormone. The major part (approximately 85%) of the receptor bound estradiol was found associated with the extranucleolar chromatin; only a negligible amount of [3H]-estradiol (approximately 8%) sedimented with the nucleolar fraction. [3H]-estradiol labeled chromatin was then fragmented by sonication and fractionated by sucrose density gradient sedimentation under different conditions of centrifugation. The vast majority of the [3H]-estradiol was invariably found to be associated with a fast sedimenting fraction which contained only 5 to 10% of the nuclear DNA. The concentration of estradiol receptors (per weight of DNA) in this fraction was 25- to 50-fold higher than that found in the slow sedimenting major chromatin component. Chemical analysis showed this fraction to have a high protein/DNA ratio but no phospholipids were detected.
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000032:analysis; D002843:Chromatin / Q000302:isolation & purification*; D004247:DNA / Q000032:analysis; D004717:Endometrium / Q000032:analysis*; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D011960:Receptors, Estrogen / Q000032:analysis* / Q000378:metabolism; D014599:Uterus / Q000378:metabolism
D002843:Chromatin; D011960:Receptors, Estrogen; D004958:Estradiol; D004247:DNA