THE INTERACTION OF MEMBRANE DNA-BINDING PROTEIN WITH DNA

A 31-kDa protein specifically binding to double-stranded DNA (ds-DNA) was isolated from plasmatic membranes of rat liver cells by means of a ffinity chromatography and high performance liquid chromatography (HPL C). Some of the properties of this protein were determined. Judging by the UV and circular dichroism spectroscopic data, the protein forms a complex with DNA, stabilizing its native structure, mainly in the reg ions rich in AT pairs. The 31-kDa protein-pAO3 plasmid DNA binding con stant was determined by nitrocellulose filter analysis of protein labe lled DNA complexes. The results obtained correspond to cooperative bin ding with DNA molecules of extended interacting ligands, having AT spe cificity. A possible role of the 31-kDa protein in DNA transmembrane t ransition processes is discussed.