Age-related changes of the pattern of non-histone chromatin proteins from rat and mouse liver chromatin.

The non-histone chromatin (NHC) proteins which are loosely bound to DNA were extracted from young and old mouse and rat liver chromatin by 0.35 M NaCl and fractionated into three groups: water-soluble, 0.14 M NaCl soluble and 0.35 M NaCl soluble. NHC proteins in each fraction were separated by SDS-disc polyacrylamide gel electrophoresis. Special attempts were made to locate minor high-molecular-weight proteins which develop faint bands. It was found that the aging of liver cells is associated with increase in number and quantities of high-molecular-weight NHC proteins in the water-soluble group. Salt-soluble groups of NHC proteins show fewer changes of pattern.