Presence of histone mRNA sequences in high molecular weight RNA of HeLa cells

Abstract Pulse-labeled HeLa cell RNA centrifuged under denaturing conditions was hybridized with DNA of recombinant phages containing sea urchin histone genes. This cross-hybridization showed the presence of histone mRNA sequences in high molecular weight RNA molecules. Treatment of the cells with actinomycin to stop RNA synthesis resulted in the rapid decay of this high molecular weight RNA followed by an increase of 9S histone mRNA in the cytoplasm. The results are consistent with the presence in HeLa cells of a high molecular weight precursor to histone messengers.