Large scale isoelectric focusing analysis of the non-histone proteins of the nucleus: isolation of components with alkaline isoelectric points.

After large scale isoelectric focusing of rat liver non-histone protein in polyacrylamide gel, pH range 4--8.6, the only protein material found outside the gradient was present in the cathode solution (20 mM NaOH). This was low mol. wt protein material (approximately 10,000) with an acidic amino acid composition. It bound 5--6 times its own weight of basic ampholine carrier ampholytes to give a complex with a pI of 8.82. This could be dissociated by dialysis against 1 M NaCl.