Thyroid receptor activator molecule, TRAM-1, is an androgen receptor coactivator.
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.
Tan
J A
JA
The Laboratories for Reproductive Biology, University of North Carolina School of Medicine, Chapel Hill 27599-7500, USA.
Hall
S H
SH
Petrusz
P
P
French
F S
FS
D000123:Acetyltransferases; D000728:Androgens / Q000502:physiology; D015153:Blotting, Western; D002478:Cells, Cultured; D005982:Glutathione Transferase / Q000378:metabolism; D051548:Histone Acetyltransferases; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D056920:Nuclear Receptor Coactivator 1; D056921:Nuclear Receptor Coactivator 3; D015513:Oncogene Proteins; D010957:Plasmids / Q000235:genetics; D011944:Receptors, Androgen / Q000502:physiology*; D012671:Seminiferous Tubules / Q000166:cytology / Q000378:metabolism; D013091:Spermatogenesis / Q000502:physiology; D013737:Testis / Q000166:cytology / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014162:Transfection / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism
D000728:Androgens; D015513:Oncogene Proteins; D011944:Receptors, Androgen; D015534:Trans-Activators; D014157:Transcription Factors; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; C538859:NCOA1 protein, human; C538866:NCOA3 protein, human; D056920:Nuclear Receptor Coactivator 1; D056921:Nuclear Receptor Coactivator 3; D005982:Glutathione Transferase; D001616:beta-Galactosidase