Gamma subunit of transcription initiation factor IIA, C-terminal domain
Transcription factor II A (TFIIA) is one of the general transcription factors for RNA polymerase II. TFIIA increases the affinity of the TATA-binding protein (TBP) for DNA, in order to assemble the initiation complex. TFIIA also functions as an activator during development and differentiation, and is involved in transcription from TATA-less promoters. TFIIA is composed of more than one subunit in various organisms. Mammalian TFIIA large subunits (TFIIA alpha and beta), and the smaller subunit (TFIIA gamma) form a heterotrimer. TFIIA alpha and beta are encoded by a single TFIIA_alpha_beta gene and post-translationally processed and cleaved. TOA1 and TOA2 are the two subunits of Yeast TFIIA which correspond to Mammalian TFIIA_alpha_beta and TFIIA gamma, respectively. TOA1 and TOA2 form a heterodimeric protein complex. The TFIIA gamma subunit is highly conserved between humans, Drosophila and yeast and it is required for TFIIA function. The C-terminal domain of the gamma (TFIIA_gamma_C) subunit forms a beta-barrel structure together with TFIIA beta.
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