Nuclear binding and sedimentation properties of two activated forms of glucocorticoid-receptor complexes from rat mammary glands.

Mammary cytoplasmic glucocorticoid-receptor complexes, which had been exposed to a high concentration of ammonium sulfate, were found to be separated into two receptor forms, consisting of DNA-cellulose-bound and non-DNA-cellulose-bound receptors. Experiments under cell-free conditions revealed that not only the DNA-cellulose-bound receptor but also the non-DNA-cellulose-bound receptor have binding abilities to nuclei and to nuclear chromatin. In sucrose density gradient centrifugation, the non-DNA-cellulose-bound receptor sedimented at higher sedimentation coefficients than the DNA-cellulose-bound receptor under all the salt conditions tested. These data strongly suggest that in the mammary glucocorticoid receptor system there exist at least two activated receptor forms with different conformations.