Comparative studies of the 17 beta-estradiol receptors in rabbit liver, kidney and uterus

The cytosol 17 beta-estradiol receptors from rabbit kidney, liver and uterus, compared under identical experimental conditions, were similar in terms of their pH-activity profiles, dependence on incubation temperature, sensitivity to sulfhydryl reagents and steroid specificity. 17 beta-[3H]-Estradiol binding was saturable with all three tissues, having an apparent dissociation constant of 4 X 10(-10)M. The binding of 17 beta-[3H]-estradiol in kidney, liver and uterus was inhibited by estrogens, including estrogen conjugates, but not by testosterone, progesterone or cortisol. The 17 beta-estradiol receptors of liver, kidney and uterus exhibited significant differences with respect to their chromatographic behaviour on heparin-Sepharose. Furthermore, a comparison of their sucrose density gradient centrifugation patterns showed that the 17 beta-[3H]-estradiol-receptor complex of liver and kidney sedimented at 3-4 S in both low and high ionic strength media, while the uterine receptor sedimented at 7-8 S in low ionic strength media and at 4-5 S in high ionic strength media. When the liver and uterine cytosol fractions were combined the uterine receptor was altered and sedimented at 3-4 S in low ionic strength media.