Open AccessKinetics of Synthesis of Cytoplasmic Messenger‐Like RNA not Associated with Ribosomes in HeLa Cells
Author(s) -
MAURON Alex,
SPOHR Georges
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12058.x
Subject(s) - ribosome , hela , cytoplasm , messenger rna , rna , microbiology and biotechnology , kinetics , chemistry , protein biosynthesis , biology , physics , biochemistry , cell , gene , quantum mechanics
The turn‐over of cytoplasmic messenger‐like RNA not associated with polyribosomes as well as that of polyribosomal mRNA was investigated by labelling with [ 3 H]uridine in conditions of arrested ribosomal RNA and mitochondrial RNA synthesis. The synthesis of ribosomal RNA was inhibited with toyokamycin and that of mitochondrial RNA with ethidium bromide. In both accumulation kinetics and actinomycin‐D‐chase experiments, cytoplasmic messenger‐like ribonucleoprotein particles and polyribosomes were fractionated by buoyant density centrifugation in CsCl gradients. The half‐life of free mlRNA was found to be of 1–2 h whereas the bulk of polyribosomal mRNA was stable over the time period considered (up to 8 h) but with a minor short‐lived component. Purification of RNA from polyribosomes labelled under the same conditions and fractionation of it into polyadenylated and non‐polyadenylated fractions showed that this short‐lived minor component of half‐life less than 1 h is non‐polyadenylated.