Activator Of Basal Transcription 1 (ABT1)

Basal transcription of genes by RNA polymerase II requires the interaction of TATA-binding protein (TBP) with the core region of class II promoters. Identification of a novel mouse nuclear protein termed activator of basal transcription 1 (mABT1) that associates with the TATA-binding protein (TBP) and enhances basal transcription activity of class II promoters is described. The mABT1 associated with TBP in HeLa nuclear extracts and with purified mouse TBP in vitro. In addition, ectopically expressed mABT1 was coimmunoprecipitated with endogenous TBP in transfected cells. More importantly, mABT1 significantly enhanced transcription from an adenovirus major late promoter in a reconstituted cell-free system. mABT1 is a novel TBP-binding protein which can function as a basal transcription activator.