Cloning of an intrinsic human TFIID subunit that interacts with multiple transcriptional activators

TFIID is a multisubunit protein complex comprised of the TATA-binding protein (TBP) and multiple TBP-associated factors (TAFs). The TAFs in TEIID are essential for activator-dependent transcription. The cloning of a complementary DNA encoding a human TFIID TAF, TAF_II55, that has no known homolog in Drosophila TFIID is now described. TAF_II55 is shown to interact with the largest subunit (TAF_II230) of human TFIID through its central region and with multiple activators-including Sp1, YY1, USE, CTF, adenoviral E1A, and human immunodeficiency virus-type 1 Tat proteins-through a distinct amino-terminal domain. The TAF_II55-interacting region of Sp1 was localized to its DNA-binding domain, which is distinct from the glutamine-rich activation domains previously shown to interact with Drosophila TAF _II110. Thus, this human TFIID TAF may be a co-activator that mediates a response to multiple activators through a distinct mechanism.