Binding of [3H]estradiol- and [3H]H1285-receptor complexes to rabbit uterine chromatin.
In the present study we investigated the binding characteristics of estrogen and antiestrogen-receptor complexes to rabbit uterine chromatin. Activated or nonactivated estrogen receptors were partially purified by DEAE-cellulose chromatography using low (1 mM) or high (10 mM) concentrations of sodium molybdate. Activated [3H]estradiol-receptor complexes showed enhanced binding to chromatin acceptor sites unmasked by 1 M, 4 M and 6 M guanidine hydrochloride. We also examined the chromatin-binding characteristics of the estrogen receptors when bound by the high-affinity triphenylethylene antiestrogen, H1285. The acceptor site activity for the [3H]H1285-receptor complexes was markedly decreased at sites unmasked by 4 M and 6 M guanidine hydrochloride. Further, the nonactivated receptor complexes showed very low binding to deproteinized chromatin. The estrogen-receptor chromatin-acceptor sites were tissue specific and saturable. These chromatin acceptor sites differ in their affinity and capacity (number of binding sites per cell) for the estrogen- and antiestrogen-receptor complexes. Thus, we suggest that the differences in the physiological and physiochemical properties of estrogens and antiestrogens may be related to their differential interaction with uterine chromatin subfractions.
D000818:Animals; D002843:Chromatin / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D007700:Kinetics; D011817:Rabbits; D011955:Receptors, Drug; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen / Q000302:isolation & purification / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism*
D002843:Chromatin; D006146:Guanidines; D011955:Receptors, Drug; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen; D004958:Estradiol; D019791:Guanidine