Interaction of serum sex steroid-binding globulin with cell membranes of human decidual tissue

The interaction of the sex steroid-binding globulin (SBG) of human blood with plasma membranes of cells from human decidual tissue - the target tissue of estradiol - was studied. It was shown that SBG in complex with estradiol is capable of interacting specifically with these membranes. The dissociation (K/sub dis/) of this interaction is equal to (3.5 +/- 2.0) 10-12 M. The interaction of the SBG-estradiol complex with the membranes is characterized by high selectivity: such blood serum globulins as albumin, orosomucoid, transferrin, transcortin, and thyroxine-binding globulin do not compete with SBG for its binding sites on the membranes. The SBG-testosterone complex and SBG without steroid are also incapable of interacting with the membranes