The general transcription factor, TFIID, consists of the TATA-binding protein (TBP) associated with a series of TBP-associated factors (TAFs) that together participate in the assembly of the transcription preinitiation complex. The conserved region is found at the C-terminal of most member proteins. The crystal structure of hTAFII28 with hTAFII18 shows that this region is involved in the binding of these two subunits. The conserved region contains four alpha helices and three loops arranged as in histone H3.
Jiyao W et al.(2023). "The conserved domain database in 2023.",