Genomic footprinting reveals cell type-specific DNA binding of ubiquitous factors

摘要: Using in vivo dimethylsulfate footprinting, we have analyzed protein-DNA interactions within two regions upstream of the tyrosine aminotransferase (TAT) gene that are characterized by an altered chromatin structure TAT-expressing as compared to nonexpressing cells. All identified protein contacts DNA found exclusively hepatoma In vitro analyses specific DNA-binding factors crude nuclear extracts yield DNAase I footprints correlate well with binding sites vivo. Surprisingly, all activities present nuclei and cells, indicating mere presence is not sufficient for their interaction a site Genomic sequencing reveals methylation CpG dinucleotides whereas no at cytosine residue footprint region prevents factor its site.