Thyroid receptor activator molecule, TRAM-1, is an androgen receptor coactivator

Endocrinology. 2000 Sep;141(9):3440-50. doi: 10.1210/endo.141.9.7680.


An androgen receptor (AR) interacting protein was isolated from a HeLa cell complementary DNA library by two-hybrid screening in yeast using the AR DNA and ligand binding domains [amino acids (aa) 481-919] as bait. AR binding of the protein in yeast was dependent on the presence of testosterone or dihydrotestosterone (DHT). The isolated protein is identical to thyroid receptor activator molecule TRAM-1 but lacking aa 1-458. TRAM-1 is a steroid receptor coactivator-3 (SRC-3) subtype. In affinity matrix assays, 35S-labeled TRAM-1 bound the GST-AR ligand binding domain (aa 624-919) and GST-AR N-terminal and DNA binding domains (aa 1-660), but not the GST-AR DNA binding domain (aa 544-634) alone. Coexpression of TRAM-1 increased DHT-dependent AR transactivation 5-fold and constitutive activity of AR (aa 1-660) N-terminal and DNA-binding domains increased 9-fold. Full-length TRAM-1 (aa 1-1424) and the partial (aa 459-1424) were AR and GR coactivators as was SRC-1. In human testis, immunostaining of SRC-3 colocalized with AR in nuclei of Sertoli cells and peritubular myoid cells, indicating it could function as an AR coactivator in these cells. SRC-3 was also present in nuclei of spermatogenic cells where AR was not expressed, suggesting it might also be a coactivator with other nuclear receptors that regulate spermatogenesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetyltransferases
  • Androgens / physiology
  • Blotting, Western
  • Cells, Cultured
  • Glutathione Transferase / metabolism
  • Histone Acetyltransferases
  • Humans
  • Immunohistochemistry
  • Male
  • Nuclear Receptor Coactivator 1
  • Nuclear Receptor Coactivator 3
  • Oncogene Proteins
  • Plasmids / genetics
  • Receptors, Androgen / physiology*
  • Seminiferous Tubules / cytology
  • Seminiferous Tubules / metabolism
  • Spermatogenesis / physiology
  • Testis / cytology
  • Testis / metabolism
  • Trans-Activators / metabolism
  • Transcription Factors / metabolism
  • Transcription Factors / physiology*
  • Transfection / genetics
  • beta-Galactosidase / metabolism


  • Androgens
  • Oncogene Proteins
  • Receptors, Androgen
  • Trans-Activators
  • Transcription Factors
  • Acetyltransferases
  • Histone Acetyltransferases
  • NCOA1 protein, human
  • NCOA3 protein, human
  • Nuclear Receptor Coactivator 1
  • Nuclear Receptor Coactivator 3
  • Glutathione Transferase
  • beta-Galactosidase