Transcription Factor II A

protein
Name = general transcription factor IIA, 1, 19/37kDa
caption =


width =
HGNCid = 4646
Symbol = GTF2A1
AltSymbols =
EntrezGene = 2957
OMIM = 600520
RefSeq = NM_201595
UniProt = P52655
PDB =
ECnumber =
Chromosome = 14
Arm = q
Band = 31
LocusSupplementaryData = protein
Name = general transcription factor IIA, 2, 12kDa
caption =


width =
HGNCid = 4647
Symbol = GTF2A2
AltSymbols =
EntrezGene = 2958
OMIM = 600519
RefSeq = NM_004492
UniProt = P52657
PDB =
ECnumber =
Chromosome = 15
Arm = q
Band = 21.3
LocusSupplementaryData =

Transcription factor TFIIA is a nuclear protein involved in the RNA polymerase II-dependent transcription of DNA.cite journal | author = Høiby T, Zhou H, Mitsiou DJ, Stunnenberg HG | title = A facelift for the general transcription factor TFIIA | journal = Biochim. Biophys. Acta | volume = 1769 | issue = 7-8 | pages = 429–36 | year = 2007 | pmid = 17560669 | doi = 10.1016/j.bbaexp.2007.04.008 | issn = ] TFIIA is one of several general (basal) transcription factors (GTFs) that are required for all transcription events that use RNA polymerase II. Other GTFs include TFIID, a complex composed of the TATA binding protein TBP and TBP-associated factors (TAFs), as well as the factors TFIIB, TFIIE, TFIIF, and TFIIH. Together, these factors are responsible for promoter recognition and the formation of a transcription preinitiation complex (PIC) capable of initiating RNA synthesis from a DNA template.

Functions

TFIIA interacts with the TBP subunit of TFIID and aids in the binding of TBP to TATA-box containing promoter DNA. Although TFIIA does not recognize DNA itself, its interactions with TBP allow it to stabilize and facilitate formation of the PIC. Binding of TFIIA to TBP also results in the exclusion of negative (repressive) factors that might otherwise bind to TBP and interfere with PIC formation. TFIIA also acts as a coactivator for some transcriptional activators, assisting with their ability to increase, or activate, transcription. The requirement for TFIIA in in vitro (cell-free) transcription systems has been variable, and it can be considered either as a GTF and/or a loosely associated TAF-like coactivator. Genetic analysis in yeast has shown that TFIIA is essential for viability.

TFIIA genes

TFIIA is encoded by two separate genes, one of which encodes a large subunit (TFIIAalpha/beta, TFIIAL, TOA1; gene name gene|GTF2A1)cite journal | author = DeJong J, Roeder RG | title = A single cDNA, hTFIIA/alpha, encodes both the p35 and p19 subunits of human TFIIA | journal = Genes Dev. | volume = 7 | issue = 11 | pages = 2220–34 | year = 1993 | pmid = 8224848 | doi = 10.1101/gad.7.11.2220 | issn = ] and another which encodes a small subunit (TFIIAgamma, TFIIAS, TOA2; gene name gene|GTF2A2).cite journal | author = Ozer J, Moore PA, Bolden AH, Lee A, Rosen CA, Lieberman PM | title = Molecular cloning of the small (gamma) subunit of human TFIIA reveals functions critical for activated transcription | journal = Genes Dev. | volume = 8 | issue = 19 | pages = 2324–35 | year = 1994 | pmid = 7958899 | doi = 10.1101/gad.8.19.2324 | issn = ] In humans, the sizes of the encoded proteins are approximately 55 kD and 12 kD. Both genes are present in species ranging from humans to yeast, and their protein products interact to form a complex composed of a beta barrel domain and an alpha helical bundle domain. It is the N-terminal and C-terminal regions of the large subunit that participate in interactions with the small subunit. These regions are separated by another domain whose sequence is always present in large subunits from various species but whose size varies and whose sequence is poorly conserved. The large subunit is often observed to be proteolytically processed into two smaller subunits (alpha and beta) of approximately 35 kD and 19 kD. A second gene encoding a large TFIIA subunit has been found in some higher eukaryotes. This gene, ALF/TFIIAtau (gene name GTF2A1LF) is expressed only in oocytes and spermatocytes, suggesting it has a TFIIA-like regulatory role for gene expression only in germ cells.

References

External links

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