title: A comparative study of electrophoretic mobilities of [3H]-estradiol and monohydroxytamoxifen binding components in the cytosols of human breast carcinomas and sera of healthy adult females.
abstract: Cytosols from human breast carcinomas rich in estrogen receptors (ER) were examined for the presence of [3H]-estradiol (E2) and [3H]-monohydroxytamoxifen (OH-TX) binding components. Polyacrylamide gel electrophoresis was used to examine the comparative anodal mobilities of ER-[3H]-E2 and ER-[3H]-OH-TX complexes, and also to identify any cytosol or serum component that may exhibit preferential high affinity to OH-TX. We have demonstrated that [3H]-OH-TX binds ER with high affinity and the anodal mobility of ER-[3H]-OH-TX complexes is identical to that of ER-[3H]-E2 complexes. We were unable to identify an antiestrogen-specific component in ER-positive or ER-negative cytosols or in sera of healthy adult females. A serum component exhibiting a higher affinity to [3H]-OH-TX and [3H]-DES than to [3H]-E2 has been identified in all the female sera examined, but this binding is of high capacity and is unsaturable by a 1000-fold molar excess of unlabeled E2 or antiestrogens. The electrophoretic mobility of this component is comparable to that of serum albumin.
mesh_terms: D000328:Adult; D001665:Binding Sites; D001943:Breast Neoplasms / Q000032:analysis* / Q000378:metabolism; D003600:Cytosol / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004958:Estradiol / Q000378:metabolism; D004965:Estrogen Antagonists / Q000378:metabolism; D005260:Female; D006801:Humans; D011955:Receptors, Drug; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen / Q000032:analysis* / Q000378:metabolism*; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism
chemical_list: D004965:Estrogen Antagonists; D011955:Receptors, Drug; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen; D013629:Tamoxifen; C016601:afimoxifene; D004958:Estradiol