Glucocorticoid-binding Proteins of Rat Liver Cytosol I. SEPARATION AND IDENTIFICATION OF THE BINDING PROTEINS

摘要: Abstract The specific interaction of glucocorticoid hormones with liver cytosol proteins adrenalectomized rats was studied by an adsorbent technique for the separation free and protein-bound steroid. By this rapid procedure a high affinity binding site glucocorticoids can be detected which is usually overlooked when slower equilibrium dialysis used. This metastable protein quantitatively estimated in whole preparations because its not only natural but also [3H]dexamethasone, does bind to other two more stable glucocorticoid-binding previously reported rat cytosol, A B proteins. It distinguished from these on basis differential fractionation physical properties. Unlike proteins, sucrose gradients sediment at 4 S independently ionic strength, dexamethasone-binding sediments low salt largely as heavy complex, 7 S, reverts lighter form, presence 0.3 m KCl. similar salt-dependent behavior observed upon chromatography through Sephadex G-200 columns. fact that dexamethasone target cells, conjunction presented evidence relation hormonal enzyme induction vivo, makes it reasonable assume protein, we will call G may indeed represent physiologically significant hepatic receptor.