Regulates transcription in association with TATA binding protein (TBP). Removes TBP from the TATA box via its C-terminal ATPase activity. Both transcription activation and repression require its ATPase activity. Forms a complex with TBP which binds TATA DNA with high affinity but with altered specificity. Localized on chromatin. Specifically localized to the promoters of the genes it regulates. Present with 6560 molecules/cell in log phase SD medium. Belongs to the SNF2/RAD54 helicase family.