The general transcription factor TFIID is key in the regulation of gene transcription by RNA polymerase II and is composed of the TATA-binding protein (TBP) and at least 14 additional TBP-associated factors (TAFs). It mediates activities such as core promoter recognition and chromatin modification, necessary for the regulation of transcription. Individual TAFs are important for mediating distinct activator-specific transcriptional regulation in vivo PMID:17483474.

Structural domains comprising this superfamily share the structure of the TAF homology (TAFH), or Nervy homology region 1 (NHR1), domain which is present in eukaryotic proteins of the MTG/ETO family and whereof the core residues occur in TAF proteins. The TAFH/NHR1 domain can be involved in protein-protein interactions, e.g in MTG8/ETO with HSP90 and Gfi-1 PMID:10076566.