Adenovirus E1A protein activation of an integrated viral gene.

Adenovirus early region 1A (E1A) protein stimulates transcription from five viral promoters during the early phase of infection. This protein also stimulates transcription from non-viral genes which are newly introduced into cells by infection or transfection, but not from the endogenous copies of these non-viral genes. Here we show that E1A protein induces expression of an early adenovirus gene integrated into the chromosomal DNA of stably transformed cells. This induction requires the continuous expression of the same E1A protein which stimulates transcription of newly introduced genes. Thus, although the activity of E1A protein is not highly sequence specific, since it can stimulate transcription from newly introduced non-viral genes, the results reported here indicate that it displays some degree of sequence specificity in that an endogenous adenovirus transcription unit responds differently from most cellular genes.