Identification of Regulatory Protein- Binding Sites in Cytochrome P450 Genes by Means of the Gel- Retardation Assay

The gel-retardation, band-shift, or electromobility shift assay is used to investigate protein—DNA interactions. Nuclear protein from the desired source is incubated with a radiolabeled DNA fragment. The products of the reaction are then analyzed by electrophoresls through a nondenaturing polyacrylamide gel. Free DNA will migrate rapidly through the gel, but DNA bound to protein will move more slowly, i.e., the migration of bound DNA ts retarded. The protein-DNA complexes formed can be detected by autoradiography.