In Vitro Binding of Tritiated Hormone-Cytostatic Complexes in the Cytosol of Various Rat Tissues and the Incorporation of These Complexes Into Nuclei

Abstract

Cytosols from rat ventral prostate, liver and muscle were incubated with tritiated estrogen-cytostatic complexes or tritiated estrogen alone. Considerably more radioactivity was recovered in the 4 S region when samples from ventral prostate cytosol were analysed by sucrose density gradient centrifugation compared with samples from liver or muscle cytosols. Similar results were found using Sephadex gel filtration. However, when cytosols were incubated with tritated estrogen alone only unspecific binding was registered. After in vitro tissue incubation with the tritiated hormone-cytostatic complexes, radioactivity was found in purified nuclei of both ventral prostate and liver tissue. The possible nature of the macromolecules which bind hormone-cytostatic complexes is discussed.