Transformed glucocorticoid receptors consist of multiple subspecies with differing capacities to bind DNA-cellulose

The glucocorticoid receptor can be transformed into a DNA-binding protein by a process that is both hormone and temperature dependent. We have used a modification of the conventional method of anion-exchange chromatography to separate and analyze a variety of receptor subspecies that result from this transition. One receptor form (peak A) was found to have a capacity to bind DNA-cellulose which was significantly greater than that of the other species. Under conditions of mild heating (15 degrees C), the relative abundance of peak A in the receptor population and the rate of receptor transformation were both increased as a result of incubating samples with alkaline phosphatase. The mechanism appears to involve the conversion of the more "acidic" forms into that of peak A. The results indicate that receptor transformation is a multistep process which may be promoted by the removal of phosphate from either the receptor or a receptor-bound regulatory factor.