| Abstract: | The effects of rabbit polyclonal antibodies (AB) against an unusual estrogen-binding protein (UEBP) isolated from rat liver by immunoadsorption on the interaction of 3H]estradiol with UEBP, estrogen receptors of uterus and other tissues, of 3H]dihydroxytestosterone with prostate androgen receptors, of 3H]progesterone with uterine progesterone receptors and of 3H]dexamethazone with rat thymus glucocorticoid receptors were investigated. It was shown that preincubation of cytosol of the above tissues with AB decreases the ability of UEBP, estrogen and androgen receptors to bind the corresponding ligands. The hormone-binding activity of progesterone and glucocorticoid receptors in the presence of AB remains thereby unchanged. The binding activity of UEBP in the presence of ABUEBP diminishes due to the decrease in the concentration of protein binding sites, whereas that of estrogen and androgen receptors decreases due to the diminution of affinity for their ligands which, in turn, is the result of reduction of the association rate constant. A cross influence of AB on the activity of uterine estrogen receptors of rabbit, guinea pig and mouse was observed. It was assumed that the structure of UEBP and sex steroid receptors has some similar elements. |
