Incorporation of [7-3H]cholesterol into chromatin fractions of Ehrlich ascites tumour cells.

Incorporation in vivo of 3H-cholesterol into chromatin and its distribution among chromatin subfractions (DNA, histone, nonhistone proteins) of Ehrlich ascites tumour cells were studied. The majority of labeling appeared in the nonhistone fraction and only a slight incorporation or tracer amounts of 3H-labeling was found in the histone and DNA fractions. The 3H-labeling from 3H-cholesterol appeared predominantly in the non esterified cholesterol fractions. Our suggestion that neutral lipids--besides phospholipids--may also contribute to the regulatory functions of nonhistone chromosomal proteins needs further investigations.