Transcription factor II D

Transcription factor II D (TFIID) is one of several general transcription factors that make up the RNA polymerase II preinitiation complex. 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. Before the start of transcription, the transcription Factor II D (TFIID) complex binds to the core promoter DNA of the gene through specific recognition of promoter sequence motifs, including the TATA box, Initiator, Downstream Promoter, Motif Ten, or Downstream Regulatory elements.[1]

Functions
  • 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

Structure

TFIID is itself composed of TBP and several subunits called TATA-binding protein Associated Factors (TBP-associated factors, or TAFs). In a test tube, only TBP is necessary for transcription at promoters that contain a TATA box.[2] TAFs, however, add promoter selectivity, especially if there is no TATA box sequence for TBP to bind to.[1] TAFs are included in two distinct complexes, TFIID[3] and B-TFIID.[4] 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.[5] 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.[5]

Subunits in the TFIID complex include:[2]

See also

References
  1. Louder, RK; He, Y; López-Blanco, JR; Fang, J; Chacón, P; Nogales, E (2016). "Structure of promoter-bound TFIID and model of human pre-initiation complex assembly". Nature. 531 (7596): 604–609. Bibcode:2016Natur.531..604L. doi:10.1038/nature17394. PMC 4856295. PMID 27007846.
  2. Lee, Tong Ihn; Young, Richard A. (2000). "Transcription of eukaryotic protein-coding genes". Annu. Rev. Genet. 34: 77–137. doi:10.1146/annurev.genet.34.1.77. PMID 11092823.
  3. Dynlacht, Brian David; Hoey, Timothy; Tjian, Robert (Aug 1991). "Isolation of co-activators associated with the TATA-binding protein that mediate transcriptional activation". Cell. 66 (3): 563–576. doi:10.1016/0092-8674(81)90019-2. PMID 1907890. S2CID 5000858.
  4. "NCBI Entrez GeneID: 9044 BTAF1 BTAF1 RNA polymerase II, B-TFIID transcription factor-associated, 170 kDa (Mot1 homolog, S. cerevisiae)".
  5. Timmers, H.; Meyers, RE; Sharp, PA (Sep 1992). "Composition of transcription factor B-TFIID". Proc Natl Acad Sci USA. 89 (17): 8140–4. Bibcode:1992PNAS...89.8140T. doi:10.1073/pnas.89.17.8140. PMC 49872. PMID 1387711.
  6. Duttke, SH (March 2015). "Evolution and diversification of the basal transcription machinery". Trends in Biochemical Sciences. 40 (3): 127–9. doi:10.1016/j.tibs.2015.01.005. PMC 4410091. PMID 25661246.


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