General transcription factor that functions at the core of the DNA-binding multiprotein factor TFIID. Binding of TFIID to the TATA box is the initial transcriptional step of the pre-initiation complex (PIC), playing a role in the activation of eukaryotic genes transcribed by RNA polymerase II. Belongs to the TFIID complex which is composed of TATA binding protein (Tbp) and a number of TBP-associated factors (Tafs). Binds DNA as monomer. Interacts with TFIIA-L heterotrimer. Interacts with Taf1, Taf2, Taf5 and Taf12. Belongs to the TBP family.