Role of Pro-637 and Gln-642 in human glucocorticoid receptors and Ser-843 and Leu-848 in mineralocorticoid receptors in their differential responses to cortisol and aldosterone

J Steroid Biochem Mol Biol. 2016 May:159:31-40. doi: 10.1016/j.jsbmb.2016.02.017. Epub 2016 Feb 22.


Mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) are descended from a common ancestral corticoid receptor. The basis for specificities of human MR for aldosterone and human GR for glucocorticoids, such as cortisol, bearing 17α-hydroxyl-groups, is incompletely understood. Differences in MR at S843 and L848 and GR at the corresponding P637 and Q642 have been proposed as important in their different responses to glucocorticoids with 17α-hydroxyl-groups. We investigated the impact of these residues on binding affinity (Ki) and transcriptional activation (EC50) of mutants MR-S843P, MR-L848Q and MR-S843P/L848Q and mutants GR-P637S, GR-Q642L and GR-P637S/Q642L in the presence of different corticosteroids. Aldosterone, cortisol and corticosterone had similar affinities for wild-type MR and all mutants, while dexamethasone had increased affinity for the three mutants. However, transactivation of MR-S843P and MR-S843P/L848Q by all four steroids was significantly lower than for wild-type MR. In contrast, transactivation of MR-L848Q tended to be 3-fold higher for cortisol and corticosterone and increased 7-fold for dexamethasone, indicating that MR-L848Q has an increased response to glucocorticoids, while retaining a strong response to aldosterone. Compared to wild-type GR, GR-P637S and GR-Q642L had increased affinities and significantly increased transcriptional activity with aldosterone and corticosterone, and GR-P637S had similar transcriptional activity with cortisol and dexamethasone, while GR-Q642L and GR-P637S/Q642L had a significant decrease in transcriptional activity with cortisol and dexamethasone. 3D-models of these MR and GR mutants revealed that dexamethasone and aldosterone, respectively, fit nicely into the steroid-binding pocket, consistent with the affinity of dexamethasone for MR mutants and aldosterone for GR mutants.

Keywords: Aldosterone; Cortisol; Evolution; Glucocorticoid receptor; Mineralocorticoid receptor; Site-directed mutagenesis; Structural modelling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldosterone / physiology*
  • Amino Acid Substitution
  • Binding Sites
  • Conserved Sequence
  • Dexamethasone
  • Glutamine / chemistry
  • HEK293 Cells
  • Humans
  • Hydrocortisone / physiology*
  • Hydrogen Bonding
  • Leucine / chemistry
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Proline / chemistry
  • Protein Binding
  • Receptors, Glucocorticoid / chemistry
  • Receptors, Glucocorticoid / genetics
  • Receptors, Glucocorticoid / metabolism*
  • Receptors, Mineralocorticoid / chemistry
  • Receptors, Mineralocorticoid / genetics
  • Receptors, Mineralocorticoid / metabolism*
  • Serine / chemistry
  • Structural Homology, Protein
  • Transcriptional Activation*


  • Receptors, Glucocorticoid
  • Receptors, Mineralocorticoid
  • Glutamine
  • Serine
  • Aldosterone
  • Dexamethasone
  • Proline
  • Leucine
  • Hydrocortisone