Subunit Structure of the Glucocorticoid Receptor

Abstract

The molecular weights of specific receptors for glucocorticoids and other steroid hormones depend heavily on the conditions of investigation. High molecular weight forms of 300 000 Da and above are detected in extracts of target cells under very mild conditions of analysis which avoid subunit dissociation and denaturation. Routinely, such receptor forms are analyzed by gel permeation chromatography and sedimentation in glycerol or sucrose gradients (Sherman and Stevens 1984). On the other hand, the hormone-binding polypeptides are most easily analyzed by affinity labeling with a radiolabeled steroid derivative and subsequent SDS gel electrophoresis (Gronemeyer 1988). These receptor polypeptides form a protein family, all members of which have a similar domain arrangement even though the sizes of the polypeptides vary considerably amongst the receptors of different hormone specificities (Gehring 1987; Evans 1988). They all contain a central DNA binding domain of less than 70 amino acid residues and a carboxy terminal region of more than 200 amino acids which is involved in hormone binding.