Characteristics of a transcortin-binding component of the plasma membrane of cells of the human decidual endometrium

A sialoglycoprotein was isolated by affinity chromatography on immobilized transcortin from plasma membranes of human decidual endometrium cells, whose components were labeled with 125I and solubilized with sodium cholate. The apparent molecular mass of the monomer is 20.0 +/- 1.5 kDa, pI is at pH 3.3. The sialoglycoprotein specifically binds transcortin complexed to progesterone with Kd approximately 10(-10) M.