Recognition of non-B DNA structures by cellular proteins.

By utilising a gel retardation assay, cytoplasmic extracts of Hela cells have been shown to contain a number of polypeptides which bind preferentially to non-B forms of DNA. These polypeptides vary in apparent molecular weights and are present as minor components of the total extract. Similar properties were demonstrated by purified preparations of eukaryotic topoisomerase I and by a DNA binding subunit of the transcription factor NFkB. These results suggest that non-B DNA binding proteins may represent families of proteins which recognise more open forms of DNA as a cognate parameter to their cellular functions.