Separation of the Transcriptional Coactivator and Antirepression Functions of Transcription Factor IIA

Human transcription factor IIA (TFIIA) is composed of three subunits (α , β , and γ ). TFIIA interacts with the TATA-box binding protein and can overcome repression of transcription. TFIIA was found to be necessary for VP16-mediated transcriptional activation through a coactivator function. We have separated the coactivator and antirepression activities of TFIIA. A TFIIA lacking the α subunit was isolated from HeLa cells. This ``mini-TFIIA'' interacts with the TATA-box binding protein and can overcome repression of transcription, but it is defective in transcriptional coactivator function.