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Title: Tfiid  
Author: World Heritage Encyclopedia
Language: English
Subject: Transcription factor, TATA box, Robert G. Roeder, General transcription factor, TATA-binding protein, Transcription factor II A
Publisher: World Heritage Encyclopedia


RNA polymerase II holoenzyme is a form of eukaryotic RNA polymerase II that is recruited to the promoters of protein-coding genes in living cells. It consists of RNA polymerase II, a subset of general transcription factors, and regulatory proteins known as SRB proteins. Transcription factor II D (TFIID) is one of several general transcription factors that make up the RNA polymerase II preinitiation complex. Before the start of transcription, the transcription Factor II D (TFIID) complex binds to the TATA box in the core promoter of the gene.


  • Coordinates the activities of more than 70 polypeptides required for initiation of transcription by RNA polymerase II
  • Binds to the core promoter to position the polymerase properly
  • Serves as the scaffold for assembly of the remainder of the transcription complex
  • Acts as a channel for regulatory signals


TFIID is itself composed of several subunits called TBP-associated factors (TAFs), In a test tube, only TBP is necessary for transcription at promoters that contain a TATA box.[1] TAFs, however, add promoter selectivity, especially if there is no TATA box sequence for TBP to bind to. TAFs are included in two distinct complexes, TFIID[2]and B-TFIID.[3] The TFIID complex is composed of TBP and more than eight TAFs. But, the majority of TBP is present in the B-TFIID complex, which is composed of TBP and TAFII170 (BTAF1) in a 1:1 ratio.[4] TFIID and B-TFIID are not equivalent, since transcription reactions utilizing TFIID are responsive to gene specific transcription factors such as SP1, while reactions reconstituted with B-TFIID are not.[4]

Subunits in the TFIID complex include:[1]

See also


External links

  • Medical Subject Headings (MeSH)
  • 3D electron microscopy structures of TFIID from the EM Data Bank(EMDB)

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