TBP-associated factor explained
| Symbol: | TAF |
| TBP associated factor (TAF6) |
| Pfam: | PF02969 |
| Pfam Clan: | CL0012 |
| Interpro: | IPR004823 |
| Scop: | 1bh9 |
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 preceding transcription of DNA to RNA by RNA polymerase II.
TAFs have a signature N-terminal histone-like fold domain (HFD). 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 do not have a histone-like fold domain.[3]
Other complexes
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
Assorted signatures
TAF domains are spread out across many digital signatures:
Notes and References
- Demény MA, Soutoglou E, Nagy Z, Scheer E, Jànoshàzi A, Richardot M, Argentini M, Kessler P, Tora L . Identification of a small TAF complex and its role in the assembly of TAF-containing complexes . PLOS ONE . 2 . 3 . e316 . March 2007 . 17375202 . 1820849 . 10.1371/journal.pone.0000316 . 2007PLoSO...2..316D . free .
- Furukawa T, Tanese N . Assembly of partial TFIID complexes in mammalian cells reveals distinct activities associated with individual TATA box-binding protein-associated factors . The Journal of Biological Chemistry . 275 . 38 . 29847–56 . September 2000 . 10896937 . 10.1074/jbc.M002989200 . free .
- Friedrich JK, Panov KI, Cabart P, Russell J, Zomerdijk JC . TBP-TAF complex SL1 directs RNA polymerase I pre-initiation complex formation and stabilizes upstream binding factor at the rDNA promoter . The Journal of Biological Chemistry . 280 . 33 . 29551–8 . August 2005 . 15970593 . 3858828 . 10.1074/jbc.M501595200 . free .
- Bonnet J, Wang CY, Baptista T, Vincent SD, Hsiao WC, Stierle M, Kao CF, Tora L, Devys D . The SAGA coactivator complex acts on the whole transcribed genome and is required for RNA polymerase II transcription . Genes & Development . 28 . 18 . 1999–2012 . September 2014 . 25228644 . 4173158 . 10.1101/gad.250225.114 .
- Martinez E, Palhan VB, Tjernberg A, Lymar ES, Gamper AM, Kundu TK, Chait BT, Roeder RG . Human STAGA complex is a chromatin-acetylating transcription coactivator that interacts with pre-mRNA splicing and DNA damage-binding factors in vivo . Molecular and Cellular Biology . 21 . 20 . 6782–95 . October 2001 . 11564863 . 99856 . 10.1128/MCB.21.20.6782-6795.2001 .
- Xie X, Kokubo T, Cohen SL, Mirza UA, Hoffmann A, Chait BT, Roeder RG, Nakatani Y, Burley SK . Structural similarity between TAFs and the heterotetrameric core of the histone octamer . Nature . 380 . 6572 . 316–22 . March 1996 . 8598927 . 10.1038/380316a0 . 1996Natur.380..316X . 4329570 .
