title: Protamine-precipitated estrogen receptor: a solid-phase ligand exchange assay.
abstract: Cytoplasmic estrogen receptor can exist either free (R) or bound to estradiol-17beta (RE). Both forms can be precipitated from cytosols by protamine sulfate. After protamine precipitation R binds 3-H-estradiol-17beta quantitatively at either 0 degrees or 30 degrees, while precipitated RE binds 3-H-estradiol-17beta only at 30 degrees by exchanging with previously bound hormone. Using these observations, we have developed a method for separate determination of both cytoplasmic R and RE. This method should also be applicable for assay of other steroid receptors, especially in cases where interfering components are present in the whole cytosol.
mesh_terms: D000818:Animals; D002369:Castration; D002606:Charcoal; D011232:Chemical Precipitation; D003593:Cytoplasm / Q000032:analysis / Q000378:metabolism; D003911:Dextrans; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008024:Ligands; D008722:Methods; D010053:Ovary / Q000502:physiology; D011479:Protamines; D051381:Rats; D011956:Receptors, Cell Surface; D013696:Temperature; D014316:Tritium; D014599:Uterus / Q000032:analysis* / Q000166:cytology / Q000378:metabolism
chemical_list: D003911:Dextrans; D008024:Ligands; D011479:Protamines; D011956:Receptors, Cell Surface; D014316:Tritium; D002606:Charcoal; D004958:Estradiol