- Recent evidence indicates that the TATA-binding protein (TBP) is central to transcription by all three eukaryotic RNA polymerases (I, II, and III). Interestingly, the majority of the TBP does not appear to be free protein in vivo. Instead, it is found associated with other factors (TAFs) in multisubunit complexes. The past year has brought significant advances in our understanding of the subunit compositions and biochemical functions of these complexes. In addition, the crystal structures of the TBP core domain and the TBP-TATA box DNA complex provide new insights into how this small protein might interact with many different partners.