Acis-acting transcription element of the c-mycgene can assume an H-DNA conformation

I have used chemical probes and an oligonucleotide-association assay to determine the structure of a nuclease-sensitive, c-myc DNA region. I find that this DNA region can form a triplex-single stranded conformer in vitro--the H-DNA conformer. This DNA region has been shown previously to be a positive, cis-acting transcription element of the c-myc gene and to bind nuclear factors, including a base-paired ribonucleoprotein. Therefore, H-DNA may be a functionally important in vivo topoisomer where the H-DNA and B-DNA conformers have different transcriptional activities.