DNA-cellulose column chromatography of phosphorylated nucleolar nonhistone proteins.

A salt-extraction procedure was used to isolate a nucleolar nonhistone protein fraction, containing [32P]phosphoserine, from the nucleoli of Novikoff hepatoma ascites cells. These proteins are similar in amino-acid composition to whole nuclear (chromosomal) nonhistone proteins. DNA-cellulose column chromatography showed that this fraction contains DNA-binding phosphoproteins, some of which will bind only to homologous (Novikoff) nucleolar or nuclear DNA.