General transcription factor that plays a role in transcription initiation by RNA polymerase II (Pol II). Involved in the pre-initiation complex (PIC) formation and Pol II recruitment at promoter DNA (PubMed:
1876184, PubMed:
1946368, PubMed:
1517211, PubMed:
3818643, PubMed:
3029109, PubMed:
8413225, PubMed:
8515820, PubMed:
8516311, PubMed:
8516312, PubMed:
7601352, PubMed:
9420329, PubMed:
12931194, PubMed:
27193682). Together with the TATA box-bound TBP forms the core initiation complex and provides a bridge between TBP and the Pol II-TFIIF complex (PubMed:
8504927, PubMed:
8413225, PubMed:
8515820, PubMed:
8516311, PubMed:
8516312). Released from the PIC early following the onset of transcription during the initiation and elongation transition and reassociates with TBP during the next transcription cycle (PubMed:
7601352). Associates with chromatin to core promoter-specific regions (PubMed:
12931194, PubMed:
24441171). Binds to two distinct DNA core promoter consensus sequence elements in a TBP- independent manner; these IIB-recognition elements (BREs) are localized immediately upstream (BREu), 5'-[GC][GC][GA]CGCC-3', and downstream (BREd), 5'-[GA]T[TGA][TG][GT][TG][TG]-3', of the TATA box element (PubMed:
9420329, PubMed:
16230532, PubMed:
7675079, PubMed:
10619841). Modulates transcription start site selection (PubMed:
10318856). Exhibits also autoacetyltransferase activity that contributes to the activated transcription (PubMed:
12931194).