Hormonal regulation of an estramustine-binding protein in the submaxillary gland of the rat.

An estramustine binding protein, in many aspects similar to the prostatic secretion protein (PSP), has partly been characterized in the submaxillary gland of the male rat. The [3H]estramustine-macromolecule complex is found in the void volume of a Sephadex G 200 column, indicating a Stokes radius larger than 52 A. The estramustine binding protein is bound to Concanavalin-A, indicating a glycoprotein structure. Like PSP, the macromolecule complex that is bound to Concanavalin-A inhibits the binding of the androgen-receptor complex to DNA-cellulose. The concentration of the protein is decreased following testectomy or estrogen treatment but can be restored to normal values following testosterone administration. These results strongly indicate that the estramustine binding macromolecule in the submaxillary gland belongs to the same group of proteins as PSP. We have earlier proposed a role for PSP as an intracellular regulator of androgen activity. Based on these new results it is tempting to speculate that androgen sensitive glycoproteins may act in the same way in all androgen sensitive tissues.