Polyanion-induced release of polyribosomes from HeLa cell nuclei.

Intact detergent-washed HeLa nuclei contain a population of polyribisomes that were released by exposure to polyanions such as RNA or poly(U). The released material appeared by electron microscopic examination to be particles averaging about 200 to 300 angstroms in diameter. Sedimentation velocity analysis of the released particles indicated that the particles had S20,w values of 75 and 110. The particles stimulated amino acid incorporation in an ascites S-30 or S-100 extract at 2.5 mM Mg2+. Studies with a variety of antibiotics indicated that these polyribosomes were capable of elongating but not initiating protein synthesis. Although these polyribosomes may be of cytoplasmic origin, they appear unique in that agents thought to disperse chromatin are required for their release from the nucleus.