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

Abstract

Background: We previously identified a TBP (TATA-binding protein)-interacting protein 120A (TIP120A) from rat liver nuclear extracts. TIP120A is thought to be a unique global transcription factor that can interact with TBP and can stimulate all classes of eukaryotic transcription. Results: We produced various truncation proteins of TIP120A to delineate its 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 exhibited an ability to stimulate basal transcription in vitro. In addition, these two regions overlap with domains that facilitate nonspecific DNA-binding of RNA polymerase II. The sequences of these two regions are significantly conserved among TIP120A homologues of eukaryotes. Conclusions: TIP120A is a bipartite transcription factor, and both N-terminal and C-terminal regions exhibit TBP-binding activity and stimulate the basal transcription ability.