[Estradiol receptors in the sex organs and some other organs of male rats]

A study was made of specific binding of estradiol (E2) by cytosol and the extracts of the nuclei of the testes, the prostate, the kidneys and the liver of the sexually-mature male rats. In the cytosol of all the mentioned organs there were found macromolecules with a high affinity (Kac similar 1--4-10(9)M(-1)). Low capacity ti the hormone (Nc similar to (1--2)--minus 14 mol per 1 mg of protein) and a marked hormonal sterospecificity--only the preparations with an estrogenic activity, but not testosterone, 5alpha-dihydrotestosterone, progesterone and corticosterone competed for H-3--E2 binding. The capacity of cytosol of these organs to bind E2 apecifically was eliminated by pronase, but not by RNA-ase and DNA-ase. The mentioned properties of the E2-binding macromolecules of cytosol of the testes, the prostate, the kidneys and the liver permitted to refer them to the estrogenic protein-receptors. Specific E2-binding was also revealed in the extracts of the nuclei of these organs, but its level was extremely low.