Role of a GC-rich motif in transcription regulation of the adenovirus type 2 IVa2 promoter which lacks typical TATA-box element.

Promoter of the adenovirus type 2 IVa2 (IVa2) gene does not have a TATA-box element, hence it is considered to be a model of cellular TATA-less promoters. In vitro transcription of the IVa2 promoter in HeLa cell extracts identified a proximal cis-element around -40 relative to the transcription start site. DNase I footprint analysis revealed the presence of a DNA-binding factor which interacts with sequences ACCCCTCCCACTTAG at -50. Competition footprint analysis and sequence comparisons showed that the IVa2 proximal promoter element is equivalent to the GC-box, the Sp1-binding site.