Identification and partial characterization of specific oestrogen-binding components in human kidney.

In normal human kidney from adult males cytoplasmic components which bound 17beta-estradiol specifically and with high affinity were demonstrated by dextran-coated charcoal assay, sucrose gradient centrifugation and agar gel electrophoresis. The dissociation constant of the oestradiol-binder complex amounted to 2.2 +/- 0.1 x 10(-9) mol/l. The binding capacity was limited to 34.0 +/- 9.7 fmol/mg of cytosol protein. Sedimentation in sucrose gradient revealed the bulk of these components to be in the 4S 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 oestrogens. The fact that an excess of aldosterone had no competitive effect on oestradiol binding suggests that the oestrogen-binding sites are independent of mineralocorticoid receptors. It is concluded that the specific binding components in human kidney have the properties of oestrogen receptors.