Accurate transcription in vivo requires at least six general transcription initiation factors, in addition to RNA polymerase II. Transcription initiation factor IIA (TFIIA) is a multimeric protein which facilitates the binding of TFIID to the TATA box. The N-terminal domain of the gamma subunit is a 4 helix bundle.
Jiyao W et al.(2023). "The conserved domain database in 2023.",