Interaction of chromatin components with nuclear 5.0 S RNA fraction that stimulates RNA synthesis

Chick liver nuclear 5.0 S RNA, which stimulates RNA synthesis on chromatin, binds preferentially to the deoxyribonucleoprotein in homologous chromatin. The proteins found in the isolated deoxyribonucleoprotein-5.0 S RNA complex are total amount of both H4 and H3 histone, about 20% of nonhistone protein and about 50% of both H2a and H2b histone found in the original chromatin. Cesium chloride equilibrium centrifugation of the deoxyribonucleoprotein-5.0 S RNA complex after fixation with formaldehyde shows that the 5.0 S RNA is bound to certain proteins (acid-soluble and -insoluble) in the complex. The stimulation of RNA synthesis by the nuclear RNA fraction is due to the conversion of inaccessible region of DNA to RNA polymerase into an accessible one and presumably not due to an increase in the number of binding sites for RNA polymerase in the chromatin. The release of non-histone protein from chromatin following the addition of the nuclear RNA fraction is also briefly discussed.