Cytosolic type II estrogen binding site in rat uterus: specific photolabeling with estrone.
A low affinity (Kd = 30 nM), large capacity (Bmax = 2.6 pmol/g tissue) estrogen binding site was photolabeled from estradiol-stimulated rat uterus cytosol. To maximize levels of this binding site and reduce those of the type I binding site, ovariectomized rats were injected with high doses of estradiol (10 micrograms per day) for four days with the last injection two hours before sacrifice. This treatment depleted type I estrogen receptors from the cytosol (by 90%) and raised levels of type II sites in the nucleus without affecting cytosolic type II levels. The type II estradiol binding sites were distinguished from the type I sites on the basis of their dissociation kinetics, pH-sensitivity and their behavior towards potassium chloride, somatostatin, sodium thiocyanate, sulfhydryl reagents and ammonium sulfate precipitation. These type II binding sites could be covalently photolabeled with tritiated estrone. A molecular weight of 43 kDa was found on SDS PAGE.
Poirot
M
M
Departement d'Endocrinologie, CHU Rangueil, Toulouse, France.
Chailleux
C
C
Bayard
F
F
Faye
J C
JC
D000345:Affinity Labels; D000818:Animals; D001665:Binding Sites; D003600:Cytosol / Q000378:metabolism*; D004970:Estrone / Q000378:metabolism*; D005260:Female; D006863:Hydrogen-Ion Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D014599:Uterus / Q000378:metabolism*
D000345:Affinity Labels; D004970:Estrone