The receptor-estradiol complex formed in rat uterine cytosol when heated at 37 C converts from a dissociable to a nondissociable form. The conversion is best observed in cytosols pretreated with charcoal at 0 C which renders the subsequently formed receptor-estradiol complexes thermostable at 37 C. In the presence of dithiothreitol the heated complex remains dissociable. Tamoxifen does not form nondissociable complexes with the estradiol receptor. It is proposed that the nondissociable form of the receptor complex is a required phase in the mechanism of estradiol action.
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http://dx.doi.org/10.1016/0006-291x(85)91769-3 | DOI Listing |
Mol Endocrinol
May 2007
Department of Chemistry, CB 3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
The human nuclear pregnane X receptor (PXR) responds to a wide variety of xenobiotic and endobiotic compounds, including pregnanes, progesterones, corticosterones, lithocholic acids, and 17beta-estradiol. In response to these ligands, the receptor controls the expression of genes central to the metabolism and excretion of potentially harmful chemicals from both exogenous and endogenous sources. Although the structural basis of PXR's interaction with small and large xenobiotics has been examined, the detailed nature of its binding to endobiotics, including steroid-like ligands, remains unclear.
View Article and Find Full Text PDFInt J Oncol
September 2003
Dipartimento di Medicina Sperimentale, II Università di Napoli, Via Constantinopoli 16, I-80138 Naples, Italy.
We examined the effect of estrogens on mitogen-activated protein kinase (MAPK) in EPN cells, a line of epithelial cells derived from human normal prostate. 17beta-estradiol (E2) caused a rapid and transient activation of MAPK (ERK1/2) within 5 min. This effect was counteracted by the anti-estrogen ICI 182-780 and by MEK inhibitor PD098059.
View Article and Find Full Text PDFMech Ageing Dev
September 1992
Department of Physiology, University of Texas, Health Science Center, San Antonio 78284-7756.
Several, though not all, estrogen-dependent phenomena show reduced responsiveness to estradiol (E2) during aging. One factor contributing to this reduced sensitivity could be an increase in the dissociation rate of the estrogen receptor-hormone complex. We therefore studied the effect of aging on the dissociation rate of 3HE2 from the uterine cytosolic estrogen receptor (ER) of C57BL/6 mice that had been ovariectomized 48 h earlier.
View Article and Find Full Text PDFMol Cell Biol
January 1990
Department of Biochemistry, University of Illinois, Urbana 61801.
We have developed a transfection assay to investigate the estrogen-mediated stabilization of cytoplasmic vitellogenin mRNA. A minivitellogenin (MV5) gene containing the 5' and 3' untranslated and coding regions but lacking 5,075 nucleotides of internal coding sequence was constructed. Cotransfection of the MV5 plasmid and a Xenopus estrogen receptor expression plasmid into Xenopus liver tissue culture cells yielded a 529-nucleotide MV5 mRNA, which was specifically stabilized by estrogen.
View Article and Find Full Text PDFJ Steroid Biochem
June 1989
ORIS-Industrie, Bagnols-sur-Cèze, France.
The localization on the calf estrogen receptor of the binding domain for B36 (an IgM antibody which prevents and reverses the effects of receptor activation) has been studied by means of controlled proteolysis of the receptor-estradiol complex using trypsin, chymotrypsin, and papain. We successively determined for intact and proteolyzed receptor-estradiol complex (i) the abilities of estradiol-binding species to aggregate in low salt medium, to bind to nonspecific DNA absorbed onto cellulose, and to interact with B36 antibody in sucrose gradients; (ii) the hydrodynamic properties of estradiol-binding species, by gel permeation chromatography and sucrose gradient centrifugation in high salt media and (iii) the molecular weights of B36-reactive species, by immunoblot analysis. Three tryptic receptor fragments of Mr 36,000, 34,000, and 33,000 and two chymotryptic fragments of Mr 36,000 and 33,000 included both the hormone- and B36-binding domains but did not interact with DNA, whereas at least two receptor fragments resulting from the action of chymotrypsin and papain bound estradiol with high affinity but interacted neither with DNA nor with B36.
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