title: Assay of estradiol receptors in human breast carcinomas using the gamma emitting ligand 16 alpha [125I]iodoestradiol.
abstract: Estradiol receptors (ER) were measured in human breast carcinomas using the gamma emitting ligand 16 alpha [125]iodoestradiol. Competition experiments with excess unlabeled steroids showed that the iodoestradiol was bound specifically by the ER. The K4 of the iodo and tritium-labeled estradiol for the receptor were similar with values of 3.4 x 10(-18) M and 2.1 x 10(-10) M respectively. A comparison of ER determination in 25 human breast carcinomas using both [3H]estradiol and [125I]estradiol gave a correlation coefficient value of 0.97. It is concluded that the use of [125I]estradiol should greatly simplify the ER assay and facilitate its introduction into the routine hospital laboratory.
mesh_terms: D001943:Breast Neoplasms / Q000032:analysis*; D004958:Estradiol / Q000031:analogs & derivatives; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D009376:Neoplasms, Hormone-Dependent / Q000032:analysis*; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen / Q000032:analysis*
chemical_list: D007457:Iodine Radioisotopes; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen; D004958:Estradiol; C024871:16 alpha-iodoestradiol