Determination of glucocorticoid receptors in leukemic myeloblasts by isoelectric focusing in polyacrylamide gel

We investigated the optimal conditions for measuring glucocorticoid receptor in blast cells from patients with acute nonlymphocytic leukemia. Cytosol receptor measured with isoelectric focusing was saturated after 60 min of incubation at 0 degrees C with 100 nM of either dexamethasone or triamcinolone. Saturation was achieved when cytosol from at least 7 X 10(6) cells was used for incubation. Trypsin treatment of the cytosol resulted in a sharpened peak of receptor focusing at pH 5.6 with no loss of receptor-bound radioactivity. The two physical forms of glucocorticoid receptor were isolated with DEAE cellulose chromatography. They were both found to focus at pH 5.6 during isoelectric focusing.