INTERACTION OF RAT-LIVER GLUCOCORTICOID RECEPTOR WITH DNA

The complex of [3H]dexamethasone and rat liver receptor binds to rat liver DNA. This interaction takes place only in the presence of hormone and is enhanced by activation. No evidence of saturatability can be obtained with concentrations of steroid-receptor complexes corresponding to those observed physiologically in the intact liver cell. The binding is inhibited by high ionic strength and by millimolar concentrations of divalent cations. No species specificity was observed: the complex binds equally well to prokaryotic and eukaryotic DNAs. There was no difference between binding to native and denatured DNA. In comparable conditions twice as much [3H]dexamethasone-receptor complexes were bound by DNA than by rat liver nuclei. Thus, the interaction of steroid-receptor complexes with DNA probably does not correspond to the recognition of a few very specific sequences. It is possible that this interaction is actually operating in vivo in the intact cell. [Calf thymus DNA, Clostridium perfringens DNA, Escherichia coli DNA and Micrococcus lysodeikticus DNA were used.].