Precursor of TFIIA alpha and beta subunits and similar proteins
Transcription factor II A (TFIIA) is one of the general transcription factors for RNA polymerase II. TFIIA increases the affinity of 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 gene (TFIIA_alpha_beta), its protein product is 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. TFIIA_alpha_beta alone is sufficient for transcription in early embryogenesis, but the cleaved forms, TFIIA alpha and TFIIA beta, represent the vast majority of TFIIA in most differentiated cells. The exact functional differences between cleaved and uncleaved forms are not yet clear. This model also contains paralogs of the canonical TFIIA_alpha_beta, such as the human ALF, which may be involved in gametogenesis and early embryogenesis (and is also subject to proteolytic cleavage).
Structure:1RM1: Interface between yeast TFIIA subunits TOA1 and TOA2, contacts at 4.0 A
Comment:TFIIA is composed of more than one subunit
Comment:Yeast TFIIA is a heterodimer, the two subunits are known as TOA1 (corresponds to human TFIIA_alpha_beta) and TOA2 (corresponds to human TFIIA_gamma)
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