Homologous Superfamily

Transcription factor IIA, helical (IPR009083)

Short name: TFIIA_a-hlx

Overlapping entries


Transcription factor IIA (TFIIA) is one of several factors that form part of a transcription pre-initiation complex along with RNA polymerase II, the TATA-box-binding protein (TBP) and TBP-associated factors, on the TATA-box sequence upstream of the initiation start site. After initiation, some components of the pre-initiation complex (including TFIIA) remain attached and re-initiate a subsequent round of transcription. TFIIA binds to TBP to stabilise TBP binding to the TATA element. TFIIA also inhibits the cytokine HMGB1 (high mobility group 1 protein) binding to TBP [PMID: 12818428], and can dissociate HMGB1 already bound to TBP/TATA-box.

Human and Drosophila TFIIA have three subunits: two large subunits, LN/alpha and LC/beta, derived from the same gene, and a small subunit, S/gamma. Yeast TFIIA has two subunits: a large TOA1 subunit that shows sequence similarity to the N-terminal of LN/alpha and the C-terminal of LC/beta, and a small subunit, TOA2 that is highly homologous with S/gamma. The conserved regions of the large and small subunits of TFIIA combine to form two domains: a four-helix bundle (helical domain) composed of two helices from each of the N-terminal regions of TOA1 and TOA2 in yeast; and a beta-barrel (beta-barrel domain) composed of beta-sheets from the C-terminal regions of TOA1 and TOA2 [PMID: 8610010].

This superfamily represents the alpha-helical domain found at the N-terminal of the gamma subunit of transcription factor TFIIA.

GO terms

Biological Process

GO:0006367 transcription initiation from RNA polymerase II promoter

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0005672 transcription factor TFIIA complex

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.