Analysis of promoters of adenovirus type 12 E1A gene in a cell-free transcription system

Transcription from the E1A gene of adenovirus type 12 initiates at two sites in vivo. In this paper we analyzed the E1A promoter(s) in a cell-free transcription system. Primer extension assay revealed that transcriptions were accurately initiated at two sites apart by 140 bp. The efficiency of transcriptions from two sites was almost equal in the standard reaction. However, when transcription reaction was done following pre-incubation of a nuclear extract and template DNA in the absence of ribonucleotides, transcription from the site proximal to E1A gene significantly decreased with little effect on that from distal site. This suggests the existence of a mechanism which controls the efficiency of transcriptions from two start sites of E1A gene.