Interaction of high mobility group proteins HMG 1 and HMG 2 with nucleosomes studied by gel electrophoresis

The binding of isolated high mobility group proteins HMG (1 + 2) with nucleosomes was studied using gel electrophoresis. The interaction of HMG (1 + 2) with mononucleosomes could be detected as a new discrete electrophoretic band with a decreased mobility only after cross-linking of HMG (1 + 2)-nucleosome complex by formaldehyde. Approximately two molecules of the large HMG proteins were bound per nucleosomal particle of a DNA length of approximately 185 base pairs, lacking histones H1 and H5. Using the same techniques, no binding was observed with core particles of a DNA length of approximately 145 base pairs.