Mediator of RNA polymerase II transcription subunit 26 is an enzyme that in humans is encoded by the MED26gene.[5][6]
It forms part of the Mediator complex.
MED26 or Transcription factor IIS (TFIIS) is a transcriptionelongation factor that increases the overall transcription rate of RNA polymerase II by reactivating transcription elongation complexes that have arrested transcription. It does this through recruiting ELL/EAF- and P-TEFb- containing complexes to promoters via a direct interaction with the N-terminal domain (NTD). The MED26 NTD also binds TFIID, and TFIID and elongation complexes interact with MED26 through overlapping binding sites.
[7]
MED26 NTD may function as a molecular switch contributing to the transition of Pol II into productive elongation.
MED26 (also known as CRSP70 and ARC70), a subunit of the Mediator complex, which is required for the activity of the enhancer-binding protein Sp1.
Elongin A, a subunit of a transcription elongation factor previously known as SIII. It increases the rate of transcription by suppressing transient pausing of the elongation complex.
PPP1R10, a nuclear regulatory subunit of protein phosphatase 1 that was previously known as p99, FB19 or PNUTS.
IWS1, which is thought to function in both transcription initiation and elongation. The TFIIS N-terminal domain is a compact four-helix bundle. The hydrophobic core residues of helices 2, 3, and 4 are well conserved among TFIIS domains, although helix 1 is less conserved.[9]
Interactions
MED26 has been shown to interact with MED8,[10]Cyclin-dependent kinase 8,[10]POLR2A,[10]MED12[10] and MED28.[10] It also acts synergistically to mediate the interaction between REST (a Kruppel-type zinc finger transcription factor that binds to a 21-bp RE1 silencing element present in over 900 human genes) and Mediator.[11]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Ryu S, Zhou S, Ladurner AG, Tjian R (Feb 1999). "The transcriptional cofactor complex CRSP is required for activity of the enhancer-binding protein Sp1". Nature. 397 (6718): 446–50. doi:10.1038/17141. PMID9989412.
^Booth V, Koth CM, Edwards AM, Arrowsmith CH (October 2000). "Structure of a conserved domain common to the transcription factors TFIIS, elongin A, and CRSP70". J. Biol. Chem. 275 (40): 31266–8. doi:10.1074/jbc.M002595200. PMID10811649.{{cite journal}}: CS1 maint: unflagged free DOI (link)
