[Interaction of blood sex steroid-binding globulin with cell membranes of human decidual tissue].

The interaction of sex steroid-binding globulin (SHBG) from human blood with plasma membranes of human decidual tissue cells (estradiol target tissue) was investigated. It was shown that SHBG complexed with estradiol specifically interacts with these membranes. The dissociation constant (Kdis) for this interaction is (3.5 +/- 2.0) X 10(-12) M. The interaction of the SHBG-estradiol complex with the membranes is characterized by a high selectivity; such serum globulins as albumin, orosomucoid, transferrin, transcortin and the thyroxine-binding globulin do not compete with SHBG for the binding sites on the membranes. The SHBG-testosterone complex and SHBG alone do not interact with the membranes either.