Identification and Partial Characterization of Specific Oestrogen-Binding Components in Human Kidney

Abstract

In normal human kidney from adult males cytoplasmic components which bound 17.beta.-estradiol specifically and with high affinity were demonstrated by dextran-coated charcoal assay, sucrose gradient centrifugation and agar gel electrophoresis. The Kd of the estradiol-binder complex amounted to 2.2 .+-. 0.1 .times. 10-9 mol/l. The binding capacity was limited to 34.0 .+-. 9.7 femtomol/mg of cytosol protein. Sedimentation in sucrose gradient revealed the bulk of these components to be in the 4 S region. The binding entities could be clearly separated from sex hormone-binding globulin by agar gel electrophoresis. The ligand specificity for binding to these components indicated a requirement for estrogens. The fact that an excess of aldosterone had no competitive effect on estradiol binding suggests that the estrogen-binding sites are independent of mineralocorticoid receptors. The specific binding components in human kidney have the properties of estrogen receptors.