Characterization of transactivational property and coactivator mediation of rat mineralocorticoid receptor activation function-1 (AF-1)

Mol Endocrinol. 2000 Jun;14(6):889-99. doi: 10.1210/mend.14.6.0467.


The autonomous activation function-2 (AF-2) in the mineralocorticoid receptor (MR) E/F domain is known to play a major role in the ligand-induced transactivation function of MR; however, it remained unclear about the transactivation function of its A/B domain. We therefore tried to characterize the MR A/B domain as the AF-1 and further studied the actions of known coactivators for AF-2 in the E/F ligand-binding domain in the function of the MR A/B domain. Deletion analyses of rat and human MRs revealed that the A/B domains harbor a transactivation function acting as AF-1. The MR mutant (E959Q) with a point mutation in helix 12, which causes a complete loss of MR AF-2 activity, still retained ligand-induced transactivation function, indicating a significant role for AF-1 in the full activity of the ligand-induced MR function. Among the coactivators tested to potentiate the MR AF-2, TIF2 and p300 potentiated the MR AF-1 through two different core regions [amino acids (a.a.) 1-169, a.a. 451-603] and exhibited functional interactions with the MR A/B domain in the cultured cells. However, such interactions were undetectable in a yeast and in an in vitro glutathione-S-transferase pull-down assay, indicating that the functional interaction of TIF2 and p300 with the MR A/B domain to support the MR AF-1 activity require some unknown nuclear factor(s) or a proper modification of the A/B domain in the cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • COS Cells
  • E1A-Associated p300 Protein
  • Escherichia coli / genetics
  • Gene Deletion
  • Genetic Vectors
  • Glutathione Transferase / genetics
  • Humans
  • Nuclear Proteins / metabolism
  • Nuclear Proteins / pharmacology
  • Nuclear Receptor Coactivator 2
  • Point Mutation
  • Rats
  • Receptors, Mineralocorticoid / chemistry
  • Receptors, Mineralocorticoid / genetics
  • Receptors, Mineralocorticoid / physiology*
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae / genetics
  • Structure-Activity Relationship
  • Trans-Activators / metabolism
  • Trans-Activators / pharmacology
  • Transcription Factors / metabolism
  • Transcription Factors / pharmacology
  • Transcriptional Activation*
  • Transfection


  • NCOA2 protein, human
  • Ncoa2 protein, rat
  • Nuclear Proteins
  • Nuclear Receptor Coactivator 2
  • Receptors, Mineralocorticoid
  • Recombinant Fusion Proteins
  • Trans-Activators
  • Transcription Factors
  • E1A-Associated p300 Protein
  • Ep300 protein, rat
  • Glutathione Transferase