InterPro domain: IPR009072

Histones mediate DNA organisation and plays a dominant role in regulating eukaryotic transcription. The histone-fold consists of a core of three helices, where the long middle helix is flanked at each end by shorter ones. The histone fold is a structural element that facilitates heterodimerisation [ 1 , 2 , 3 ]. Proteins displaying this structure include the nucleosome core histones, which form octomers composed of two copies of each of the four histones, H2A, H2B, H3 and H4; archaeal histone, which possesses only the core domain part of eukaryotic histone; and the TATA-box binding protein (TBP)-associated factors (TAF), where the histone fold is a common motif for mediating TAF-TAF interactions. TAF proteins include TAF(II)18 and TAF(II)28, which form a heterodimer, TAF(II)42 and TAF(II)62, which form a heterotetramer similar to (H3-H4)2, and the negative cofactor 2 (NC2) alpha and beta chains, which form a heterodimer. The TAF proteins are a component of transcription factor IID (TFIID), along with the TBP protein. TFIID forms part of the pre-initiation complex on core promoter elements required for RNA polymerase II-dependent transcription. The TAF subunits of TFIID mediate transcriptional activation of subsets of eukaryotic genes. The NC2 complex mediates the inhibition of TATA-dependent transcription through interactions with TBP.

1. A mechanism for repression of class II gene transcription through specific binding of NC2 to TBP-promoter complexes via heterodimeric histone fold domains. EMBO J. 15, 3105-16
2. Determination of functional domains in the C subunit of the CCAAT-binding factor (CBF) necessary for formation of a CBF-DNA complex: CBF-B interacts simultaneously with both the CBF-A and CBF-C subunits to form a heterotrimeric CBF molecule. Mol. Cell. Biol. 16, 4003-13
3. The histone fold subunits of Drosophila CHRAC facilitate nucleosome sliding through dynamic DNA interactions. Mol. Cell. Biol. 25, 9886-96