Evidence that rodent epididymal sperm contain the Mr approximately 94,000 glucocorticoid receptor but lack the Mr approximately 90,000 heat shock protein.

Monoclonal antibodies directed against four different polypeptide epitopes on the Mr approximately 94,000 steroid-binding subunit of the rat liver cytosolic glucocorticoid receptor (GcR) were used to probe Western blots of epididymal spermatozoa from rats and mice. Two sperm polypeptides with apparent molecular weights of 94,000 (indistinguishable in size from the liver GcR subunit) and 150,000 reacted with these antibodies. Other polypeptides that are present in a wide variety of somatic cells [lamin-A, -B, and -C; topoisomerase-I; poly(ADP-ribose) polymerase; the 62-kilodalton internal nuclear matrix protein; the nucleolar protein B23; and histone H1] could not be detected in these preparations of spermatozoa, thus appearing to rule out contamination by somatic cells. Rat and mouse pachytene spermatocytes and round spermatids contained much lower amounts of the Mr approximately 94,000 and 150,000 polypeptides. These results suggested that the steroid-binding subunit of the GcR might be accumulated late ...