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MED1/TRAP220 Exists Predominantly in a TRAP/ Mediator Subpopulation Enriched in RNA Polymerase II and Is Required for ER-Mediated Transcription
- Source :
-
Molecular Cell . Jul2005, Vol. 19 Issue 1, p89-100. 12p. - Publication Year :
- 2005
-
Abstract
- Summary: Human TRAP/Mediator is a key coactivator for many transcription factors that act through direct interactions with distinct subunits, and MED1/TRAP220 is the main subunit target for various nuclear receptors. Remarkably, the current study shows that MED1/TRAP220 only exists in a TRAP/Mediator subpopulation (less then 20% of the total) that is greatly enriched in specific TRAP/Mediator subunits and is tightly associated with a near stoichiometeric level of RNA polymerase II. Importantly, this MED1/TRAP220-containing holoenzyme supports both basal- and activator-dependent transcription in an in vitro system lacking additional RNA polymerase II. Furthermore, chromatin immunoprecipitation experiments demonstrate an activator-selective recruitment of MED1/TRAP220-containing versus MED1/TRAP220-deficient TRAP/Mediator complexes to estrogen receptor (ER) and p53 target genes, respectively. Finally, RNAi studies show that MED1/TRAP220 is required for ER-mediated transcription and estrogen-dependent breast cancer cell growth. These observations have significant implications for our current understanding of the composition, heterogeneity, and functional specificity of TRAP/Mediator complexes. [Copyright &y& Elsevier]
- Subjects :
- *NUCLEIC acids
*RNA polymerases
*TRANSCRIPTION factors
*STEROID hormones
Subjects
Details
- Language :
- English
- ISSN :
- 10972765
- Volume :
- 19
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Molecular Cell
- Publication Type :
- Academic Journal
- Accession number :
- 18095207
- Full Text :
- https://doi.org/10.1016/j.molcel.2005.05.015