[Post-transcriptional association of RNP particles with chromatin in Zajdela ascities hepatoma cells].

The interrelationship between nuclear RNP particles and chromatin in Zajdela hepatoma cells double labelled with 3H-thymidine and 14C-uridine was investigated by three independent methods (Nucleoprotein-Celite chromatography, sucrose density and CsCl band centrifugations). All nuclear RNP particles were found to be associated with the chromatin. Some of chromatin-associated RNA molecules are polyadenylated, thus indicating the post-transcriptional character of this association. DNA and RNA molecules in these complexes are bound through protein rather than being connected directly. The site of contact between RNP particle and chromatin is relatively resistant to the action of DNase I and pancreatic RNase. The experiments with exogeneous labelled RNP particles added to isolated nuclei do not reveal the formation of artificial RNP-chromatin complexes. The results obtained are discussed in the light of current views on the nucleus-to-cytoplasm transport of RNA molecules.