Studies in steroid metabolism XVII. Intracellular distribution of [16-14C]estrone in rat liver

Liver tissue obtained from rats after short-term infusion of [16-¹⁴C]estrone was homogenized and differentially fractionated into nuclei, mitochondria, microsomes and supernatant. The greatest amount of radioactivity was found in the supernatant fraction, followed by the nuclei and mitochondria with the lowest amount in the microsomes. The highest specific activity was present in the supernatant fraction followed by the mitochondria and microsomes with the lowest value obtained for the nuclei. Examination of the individual fractions showed probable evidence for binding of estrogen to liver protein, formation of little if any conjugates, possible degradation of ring D and the production of estradiol and another substance more polar than estriol.