Abstract: An isolated mineralocorticoid receptor (MR) polypeptide, or functional portion thereof, having one or more mutations that alter the solubility or crystal-forming properties and confer the ability to generate soluble protein complexes with the MR and ligands that only weakly bind the native polypeptide, and a polynucleotide encoding it are disclosed. Representative mutations are C808S and S810L substitutions. Expression of the MR polypeptide in E. coli is also provided. A solved three-dimensional crystal structure of an MR ligand binding domain polypeptide is also disclosed, along with a crystalline form of the MR ligand binding domain polypeptide.

Abstract: A solved three-dimensional crystal structure of a glucocorticord receptor (GR) ? ligand binding domain polypeptide is disclosed, in the form of a crystalline glucocorticord receptor ? ligand binding domain polypeptide in complex with the ligand fluticasone propionate (FP) and a peptide derived from the co-activator TIF2. The GR/FP/TIF2 structure includes an expanded binding pocket not seen in other GR structures. Methods of designing steroid and non-steroid modulators of the biological activity of GR and other nuclear receptors (NRs) are also disclosed. In another aspect of the present invention homology models of androgen receptor (AR), progesterone receptor (PR) and mineralcorticoid receptor (MR) are disclosed, as well as methods of forming homology models for other NRs. Methods of forming a soluble GR/FP/TIF2 complex are also disclosed.

Abstract: A method of modifying a test nuclear receptor (NR) polypeptide is disclosed. The method provides a test NR polypeptide sequence having a characteristic that is targeted for modification; aligning the test NR polypeptide sequence with at least one reference NR polypeptide sequence for which an X-ray structure is available; building a three-dimensional model for the test NR polypeptide using the three-dimensional coordinates of the X-ray structure(s) of at least one reference polypeptide and its sequence alignment with the test NR polypeptide sequence; examining the three-dimensional model of the test NR polypeptide sequence for characteristic differences with the reference polypeptide; and mutating at least one amino acid residue in the test NR polypeptide sequence at a characteristic difference, whereby the test NR polypeptide is modified.