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Cell. 2011 Jul 8;146(1):92-104. doi: 10.1016/j.cell.2011.06.005.

Human mediator subunit MED26 functions as a docking site for transcription elongation factors.

Author information

1
Stowers Institute for Medical Research, Kansas City, MO 64110, USA.

Abstract

Promoter-proximal pausing by initiated RNA polymerase II (Pol II) and regulated release of paused polymerase into productive elongation has emerged as a major mechanism of transcription activation. Reactivation of paused Pol II correlates with recruitment of super-elongation complexes (SECs) containing ELL/EAF family members, P-TEFb, and other proteins, but the mechanism of their recruitment is an unanswered question. Here, we present evidence for a role of human Mediator subunit MED26 in this process. We identify in the conserved N-terminal domain of MED26 overlapping docking sites for SEC and a second ELL/EAF-containing complex, as well as general initiation factor TFIID. In addition, we present evidence consistent with the model that MED26 can function as a molecular switch that interacts first with TFIID in the Pol II initiation complex and then exchanges TFIID for complexes containing ELL/EAF and P-TEFb to facilitate transition of Pol II into the elongation stage of transcription.

PMID:
21729782
PMCID:
PMC3145325
DOI:
10.1016/j.cell.2011.06.005
[Indexed for MEDLINE]
Free PMC Article

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