Transcription factor Sp1 recognizes promoter sequences from the monkey genome that are simian virus 40 promoter.

A 440-base-pair fragment of African green monkey genomic DNA shares homology with the transcriptional regulatory region of simian virus 40 (SV40) and has been reported to direct transcription in vivo. We find that two regions within this fragment bind the promoter-specific cellular transcription factor Sp1 and are protected in DNase protection ("footprinting") experiments. As in SV40, binding occurs in regions containing multiple copies of the sequence GGGCGG. These regions, when fused to the proximal, or "TATA box," element of the herpes simplex virus thymidine kinase promoter, are able to direct Sp1-dependent transcription in vitro. The finding that Sp1 is capable of productive interaction with sequences taken from a cellular promoter supports the idea that Sp1 may play a role in modulating transcription of cellular genes.