New purification method for glucocorticoid receptors

In this report, we describe a new purification method for activated recombinant glucocorticoid receptor (GR) utilizing a cation-exchanger (Mono S) at pH 8.4. This method is based upon a new finding that activated GR binds to both Mono Q and Mono S columns at the same pH. This method enables us to purify recombinant GR within 3 h. The purified GR represents more than 97% of the eluted proteins. Purified recombinant GR is able to bind specifically to a DNA fragment containing the glucocorticoid response element. Recombinant GR has no tag sequence that can be utilized for purification. Thus, this separation method is also applicable to purification of native GR.