title: Simultaneous measurement of estrogen and progesterone receptors in tumor cytosols with use of 125I-labeled estradiol and of 3H-R5020.
abstract: We describe a dual-isotope assay for measuring the concentration of estrogen receptors and progesterone receptors in tumor cytosols. The concentrations of these receptors are derived from separate Scatchard-plot analyses of a single dextran-coated charcoal assay that incorporates both radioiodinated estradiol and tritiated R5020 as the labeled ligands. The two isotopes, radioiodine and tritium, are easily measured with a liquid-scintillation counter. The concentrations of estrogen and progesterone receptors derived from the dual-label assay are identical to values derived from the respective single-label assays. Moreover, values obtained from an assay with dextran-coated charcoal that incorporates radioiodinated estradiol are identical to those obtained from an assay in which tritiated estradiol is used as the labeled ligand. The dual-isotope assay requires both less time and less tissue.
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods; D007700:Kinetics; D009649:Norpregnadienes / Q000378:metabolism*; D011397:Promegestone / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D014316:Tritium; D014594:Uterine Neoplasms / Q000378:metabolism*
chemical_list: D007457:Iodine Radioisotopes; D009649:Norpregnadienes; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D014316:Tritium; D004958:Estradiol; D011397:Promegestone