• Register
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.


Leaving Community

Are you sure you want to leave this community? Leaving the community will revoke any permissions you have been granted in this community.


TRAM-1, A novel 160-kDa thyroid hormone receptor activator molecule, exhibits distinct properties from steroid receptor coactivator-1.

Nuclear hormone receptors (NRs) are ligand-dependent transcription factors that regulate target gene transcription. We report the molecular cloning and characterization of a novel human cDNA encoding TRAM-1, a thyroid hormone receptor activator molecule, a approximately 160-kDa protein homologous with SRC-1/TIF2, by far-Western-based expression screening. TRAM-1 binds to thyroid hormone receptor (TR) and other NRs in a ligand-dependent manner and enhances ligand-induced transcriptional activity of TR. The AF-2 region in NRs has been thought to play a critical role in mediating ligand-dependent transactivation by the interaction with coactivators. Surprisingly, TRAM-1 retains strong ligand-dependent interaction with an AF-2 mutant of TR (E457A), while SRC-1 fails to interact with this mutant. Furthermore, we identified a critical TRAM-1 binding site in rat TRbeta1 outside of AF-2, as TRAM-1 shows weak ligand-dependent interaction with a helix 3 ligand binding domain TR mutant (K288A), compared with SRC-1. These results suggest that TRAM-1 is a coactivator that may exhibit its activity by interacting with subdomains of NRs other than the AF-2 region, in contrast to SRC-1/TIF2.

Pubmed ID: 9346901


  • Takeshita A
  • Cardona GR
  • Koibuchi N
  • Suen CS
  • Chin WW


The Journal of biological chemistry

Publication Data

October 31, 1997

Associated Grants


Mesh Terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • DNA, Complementary
  • Histone Acetyltransferases
  • Humans
  • Molecular Sequence Data
  • Nuclear Receptor Coactivator 1
  • Nuclear Receptor Coactivator 3
  • Protein Binding
  • Rats
  • Sequence Homology, Amino Acid
  • Transcription Factors