The effect of the nonionic detergent Triton X-100 on cytoplasmic and nuclear estrogen receptors from rat uterus was determined. The cytoplasmic estrogen receptor was deaggregated from the 8S aggregate to a 4S form on sucrose gradients which contained low concentrations of Triton X-100. At concentrations of detergent great than 0.1% a partial loss of binding was observed. Estradiol dissociated more rapidly from the extracted nuclear receptor and as a consequence in the presence of detergent, only centrifugation runs of abbreviated duration (4 h) allowed the nuclear receptor to be resolved on sucrose gradients. The dissociation rate constant, k-1., of the cytoplasmic receptor was not significantly affected at 0-4°C by ionic strength or by activation of cytoplasmic receptor. Triton X-100 increased the rate of ligand dissociation from cytoplasmic estrogen receptor ~ 1.3-2.0-fold and from nuclear receptor ~ 4.5-fold. In a homogeneous environment obtained by combining cytosol and nuclear extracts, ligand dissociation from nuclear and cytoplasmic receptors proceeded at a similar velocity and this velocity was faster than previously determined for the cytoplasmic receptor under a variety of conditions. The data reported support the hypothesis that the estrogen receptor may be modified by certain factors contained in the crude nuclear pellet so that in the presence of Triton X-100 the nuclear receptor appears less able to bind estradiol.
|Number of pages||9|
|Journal||Journal of Steroid Biochemistry|
|State||Published - Dec 1980|
Bibliographical noteFunding Information:
*This work was conducted in the laboratory of Dr. Benita S. Katzenellenbogen whose support and encouragement is gratefully appreciated. This work was supported by National Institutes of Health Grants USPH HD 06726 and CA 18119 (B.S.K.), and a National Cancer Institute Postdoctoral Research Fellowship lF32 CA 06149-01 (E.J.P.). t To whom correspondence should be addressed. Present address: Department of Obstetrics and Gynecology, University of Kentucky, Albert B. Chandler Medical Center, Lexington, Kentucky 40506, U.S.A.
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