TBP-interacting protein TIP120A is a new global transcription activator with bipartite functional domains

Background: We previously identified a TBP (TATA-binding protein)-interacti ng protein 120A (TIP120A) from rat liver nuclear extracts. TIP120A is thoug ht to be a unique global transcription factor that can interact with TBP an d can stimulate all classes of eukaryotic transcription. Results: We produced various truncation proteins of TIP120A to delineate it s functional domains. TIP120A binds to TBP in the acidic amino acid-rich N- terminal region and in the leucine-rich C-terminal region. These regions ex hibited an ability to stimulate basal transcription in vitro. In addition, these two regions overlap with domains that facilitate nonspecific DNA-bind ing of RNA polymerase II. The sequences of these two regions are significan tly conserved among TIP120A homologues of eukaryotes. Conclusions: TIP120A is a bipartite transcription factor, and both N-termin al and C-terminal regions exhibit TBP-binding activity and stimulate the ba sal transcription ability.