Transcription factor Sp1 binds to and activates a human hsp70 gene promoter

I investigated the binding of purified transcription factor Sp1 from HeLa cells to the human hsp70 promoter by DNase I footprinting. Three binding sites were detected within the upstream promoter region, including one located 46 base pairs upstream of the transcription start, between the TATA box and the proximal CCAAT box element. In vitro transcription demonstrated that the proximal site is capable of responding to Sp1-dependent stimulation. These results suggest that Sp1 might contribute to constitutive expression in vivo and might also be involved in the various regulatory responses that affect this gene.