title: Estrogen and antiestrogen binding to different forms of the molybdate-stabilized estrogen receptor.
abstract: We report that the calf uterine estrogen receptor, prepared in a Tris-molybdate buffer, bound by 10 nM [3H]estradiol and eluted by a KCl gradient from DEAE-cellulose columns, yielded only one very sharp receptor peak. Estrogen receptor prepared in phosphate buffer with molybdate and eluted with KCl also yielded only one sharp peak on DEAE-cellulose. However, if DEAE-Sephadex (with phosphate buffer plus molybdate) was used, the [3H]estradiol-receptor complex eluted with two sharp peaks at approximately 0.21 and 0.25 M KCl (Peaks I and II, respectively). But the high-affinity antiestrogen, [3H]H1285, bound to estrogen receptor, eluted only as Peak I and not as Peak II. Both the [3H]estradiol and [3H]H1285 binding peaks were saturable since they could be eliminated with 200-fold excess estradiol. Therefore, ion exchange chromatography using different resins and/or buffers may be useful for determining physicochemical differences in estrogen versus antiestrogen receptor complexes.
mesh_terms: D000818:Animals; D002417:Cattle; D004355:Drug Stability; D004958:Estradiol / Q000378:metabolism*; D004965:Estrogen Antagonists / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008982:Molybdenum / Q000494:pharmacology*; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism
chemical_list: D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D004958:Estradiol; D008982:Molybdenum; C024687:sodium molybdate(VI)