[Interaction of transcortin with human syncytiotrophoblast].

Interactions of transcortin (corticosteroid-binding globulin, CBG) variants, nCBG and rCBG, present in the blood of pregnant women, and microvesicular fraction of the brush border membrane of human placental syncytiotrophoblast at 23 +/- 2 degrees C were studied. Interaction of nCBG in complex with a steroid with each of the two types for specific binding was found associated with transmembranous transfer of glycoprotein. Interaction of rCBG with binding sites of both types did not involve subsequent glycoprotein transfer through the membrane. Possibility of penetration of only one CBG variant through syncytiotrophoblast membrane suggests the presence of different mechanisms of these glycoproteins' participation in the hormonal effects of steroids associated with them.