Transcription initiation factor TFIID subunit 1, also known as transcription initiation factor TFIID 250 kDa subunit (TAFII-250) or TBP-associated factor 250 kDa (p250), is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the ''TAF1''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
Function
Initiation of
transcription by
RNA polymerase II
RNA polymerase II (RNAP II and Pol II) is a multiprotein complex that transcribes DNA into precursors of messenger RNA (mRNA) and most small nuclear RNA (snRNA) and microRNA. It is one of the three RNAP enzymes found in the nucleus of eukaryo ...
requires the activities of more than 70 polypeptides. The protein that coordinates these activities is the basal transcription factor
TFIID
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 o ...
, which binds to the core promoter to position the polymerase properly, serves as the scaffold for assembly of the remainder of the transcription complex, and acts as a channel for regulatory signals. TFIID is composed of the TATA-binding protein (
TBP) and a group of evolutionarily conserved proteins known as TBP-associated factors or TAFs. TAFs may participate in basal transcription, serve as
coactivators, function in promoter recognition or modify general transcription factors (GTFs) to facilitate complex assembly and transcription initiation. This gene encodes the largest subunit of TFIID. This subunit binds to core
promoter sequences encompassing the transcription start site. It also binds to activators and other transcriptional regulators, and these interactions affect the rate of transcription initiation. This subunit contains two independent
protein kinase
A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a fu ...
domains at the N and C-terminals, but also possesses
acetyltransferase activity and can act as a
ubiquitin
Ubiquitin is a small (8.6 kDa) regulatory protein found in most tissues of eukaryotic organisms, i.e., it is found ''ubiquitously''. It was discovered in 1975 by Gideon Goldstein and further characterized throughout the late 1970s and 1980s. Fo ...
-activating/conjugating enzyme. Two transcripts encoding different isoforms have been identified for this gene.
Histones are often acetylated to open DNA for transcription. TAF1 contains two bromodomains, which each can bind one of two acetyllysine residues at position 5 and 12 in the H4 tail, to stabilize the TBP-TATA box complex.
Clinical significance
A mutation in TAF1 was identified that contributes to a phenotype with severe intellectual disability (ID), a characteristic intergluteal crease, and distinctive facial features, including a broad, upturned nose, sagging cheeks, downward sloping palpebral fissures, prominent periorbital ridges, deep-set eyes, relative hypertelorism, thin upper lip, a high-arched palate, prominent ears with thickened helices, and a pointed chin This is a non-synonymous change in TAF1 that results in an isoleucine (hydrophobic) to threonine (polar) change on the 1337th amino acid residue in the protein (NP_001273003.1). Two other mutations were reported in TAF1 in two families with intellectual disability, although further clinical details were not reported.
Interactions
TAF1 has been shown to
interact with:
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CSNK2A1,
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CCND1,
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GTF2F1
General transcription factor IIF subunit 1 is a protein that in humans is encoded by the ''GTF2F1'' gene.
Interactions
GTF2F1 has been shown to interact with:
* CTDP1,
* GTF2H4,
* HNRPU,
* MED21,
* POLR2A,
* Serum response factor
* T ...
,
UBTF
Nucleolar transcription factor 1 is a protein that in humans is encoded by the ''UBTF'' gene.
Function
Upstream binding factor (UBF) is a transcription factor required for expression of the 18S, 5.8S, and 28S ribosomal RNAs, along with SL1 (a c ...
.
See also
*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 o ...
References
Further reading
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External links
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GeneReviews/NCBI/NIH/UW entry on X-Linked Dystonia-Parkinsonism
* http://biorxiv.org/content/early/2015/01/21/014050
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