My watch list  

Transcription Factor II A

general transcription factor IIA, 1, 19/37kDa
Symbol GTF2A1
Entrez 2957
HUGO 4646
OMIM 600520
RefSeq NM_201595
UniProt P52655
Other data
Locus Chr. 14 q31
general transcription factor IIA, 2, 12kDa
Symbol GTF2A2
Entrez 2958
HUGO 4647
OMIM 600519
RefSeq NM_004492
UniProt P52657
Other data
Locus Chr. 15 q21.3

Transcription factor TFIIA is a nuclear protein involved in the RNA polymerase II-dependent transcription of DNA.[1] 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.


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 GTF2A1)[2] and another which encodes a small subunit (TFIIAgamma, TFIIAS, TOA2; gene name GTF2A2).[3] 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.


  1. ^ Høiby T, Zhou H, Mitsiou DJ, Stunnenberg HG (2007). "A facelift for the general transcription factor TFIIA". Biochim. Biophys. Acta 1769 (7-8): 429–36. doi:10.1016/j.bbaexp.2007.04.008. PMID 17560669.
  2. ^ DeJong J, Roeder RG (1993). "A single cDNA, hTFIIA/alpha, encodes both the p35 and p19 subunits of human TFIIA". Genes Dev. 7 (11): 2220-34. doi:10.1101/gad.7.11.2220. PMID 8224848.
  3. ^ Ozer J, Moore PA, Bolden AH, Lee A, Rosen CA, Lieberman PM (1994). "Molecular cloning of the small (gamma) subunit of human TFIIA reveals functions critical for activated transcription". Genes Dev. 8 (19): 2324-35. doi:10.1101/gad.8.19.2324. PMID 7958899.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Transcription_Factor_II_A". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE