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词条 TBP-associated factor
释义

  1. Function

     TFIID  SL1   Other complexes  

  2. Structure

  3. Human genes

  4. Assorted signatures

  5. References

{{hatlink|For other meanings of TAF, see TAF.}}{{Infobox protein family
| Symbol = TAF
| Name = TBP associated factor (TAF6)
| image = PDB 1taf EBI.jpg
| caption = drosophila dtafii42/dtafii62 (like TAF6/TAF9) heterotetramer, HFD
| Pfam = PF02969
| Pfam_clan = CL0012
| InterPro = IPR004823
| PROSITE =
| MEROPS =
| SCOP = 1bh9
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}

The TBP-associated factors (TAF) are proteins that associate with the TATA-binding protein in transcription initiation. It is a part of the transcription initiation factor TFIID multimeric protein complex. It also makes up many other factors, including SL1. They mediate the formation of the transcription preinitiation complex, a step preceeding transcription of DNA to RNA by RNA polymerase II.

TAFs have a signature N-terminal histone-like fold domain (HFD).[1] This domain is implicated in the pairwise interaction among specific TAFs.[1]

Function

TFIID

TFIID plays a central role in mediating promoter responses to various activators and repressors. It binds tightly to TAFII-250 and directly interacts with TAFII-40. TFIID is composed of TATA binding protein (TBP) and a number of TBP-associated factors (TAFS).[2]

TAF is part of the TFIID complex, and interacts with the following:

  • Specific transcriptional activators
  • Basal transcription factors
  • Other TAFIIs
  • Specific DNA sequences, for example the downstream promoter element or gene-specific core promoter sequence

Due to such interactions, they contribute transcription activation and to promoter selectivity.[2]

Some pairs of TAF interact with each other to form "lobes" in TFIID. Pairs known or suggested to exist in TFIID include TAF6-TAF9, TAF4-TAF12, TAF11-13, TAF8-TAF10 and TAF3-TAF10.[1]

SL1

Selective factor 1 is composed of the TATA-binding protein and three TAF (TATA box-binding protein-associated factor) subunits (TAF1A, TAF1B, and TAF1C). These TAFs don't have a histone-like fold domain.[3]

Other complexes

{{missing information|section|subunits of SAGA and related complexes, and pair-forming therein|date=April 2019}}

TAF is a part of SAGA (SPT-ADA-GCN5 acetylase) and related coactivation complexes.[1] Such complexes acetylate histone tails to activate genes.[4] Human has three SAGA-like complexes: PCAF, TFTC (TBP-free TAF-containing complex), and STAGA (SPT3-TAF9-GCN5L acetylase). PCAF (GCN5) and KAT2A (GCN5L) are two human homologs of the yeast Gcn5.[5]

TAF8, TAF10, and SPT7L forms a small TAF complex called SMAT.[1]

Structure

The N-terminal domain of TAF has a histone-like protein fold. It contains two short alpha helices and a long central alpha helix.[6]

Human genes

{{missing information|section|TAFs in non-TF2D complexes|date=April 2019}}
  • TAF1 (TAFII250)
  • TAF2 (CIF150)
  • TAF3 (TAFII140)
  • TAF4 (TAFII130/135)
  • TAF4B (TAFII105)
  • TAF5 (TAFII100)
  • TAF6 (TAFII70/80)
    • TAF6L (PAF65A)
  • TAF7 (TAFII55)
  • TAF8 (TAFII43)
  • TAF9 (TAFII31/32)
  • TAF9B (TAFII31L)
  • TAF10 (TAFII30)
  • TAF11 (TAFII28)
  • TAF12 (TAFII20/15)
  • TAF13 (TAFII18)
  • TAF15 (TAFII68)

Assorted signatures

TAF domains are spread out across many digital signatures: