Ribonucleoprotein particles (RNPs) were extracted from monkey cell nuclei in media of low ionic strength. The rapidly labeled RNPs were comparable in terms of size, protein patterns and protein content to those extracted by sonication. The overnight labeled RNPs were homogenous (sedimenting at 60–65 S and containing RNA of 30–31S), and appear to be a subset of pre-ribosomal RNPs. This procedure produces nuclear RNPs free of contaminating chromatin. Nuclear RNPs (rapidly-labeled and overnight-labeled RNPs, extracted by either our procedure or by sonication), quantitatively precipitated in 10 mM MgCl2 when the concentration of monovalent cations was low. There was no detectable degradation of the RNA components, nor was there loss of enzymatic activity of an RNP associated protein kinase. Precipitation in Mg++ provides a rapid, gentle and convenient method of concentrating RNPs.
ASJC Scopus subject areas