INTERACTION BETWEEN TRANSCRIPTION FACTORS SP1 AND YY1

A BASAL level of transcription is usually observed when all but a smal l region of DNA has been deleted from a eukaryotic gene promoter. Thes e promoter elements, which are necessary and sufficient for specific t ranscription initiation, are referred to as minimal or core promoter e lements. One element that is commonly present in a core promoter is th e initiator. It has been demonstrated that the presence of Sp1 binding sites can greatly enhance the level of transcription initiation at in itiator elements1-4. A binding site for the YY1 transcription factor, located at the initiation site of the adeno-associated virus P5 promot er, functions as an initiator element; a synergistic enhancement of it s activity is observed in vitro when upstream Sp1 binding sites are pr esent3. Here we report that this synergistic activation probably occur s through protein-protein interactions.