Evilina Ivanova

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The metabolism of nonhistone chromosomal proteins was studied in two lines of cells showing a different degree of contact inhibition: human diploid fibroblasts, which are easily contact-inhibited, and Chinese hamster fibroblasts, which had been made to stop proliferating by fasting. By following the 3H414C ratio of [3H]tryptophan-labelled nonhistone(More)
Four types of experiment were carried out to test the recently proposed model of matrix-bound replication in eukaryotic cells. In experiments with pulse-labelling we found preferential association of newly replicated DNA with the matrix only when the procedure for isolation includes first high-salt treatment of isolated nuclei and then digestion with(More)
Digestion of chromatin with micrococcal nuclease under mild conditions results in the release of a minor chromatin fraction showing an increased RNA and non-histone protein content, a fast turnover of the non-histone proteins and the presence of rapidly labelled heterogeneous nuclear RNA (hnRNA) with half-life of about 20 min. Further digestion of the(More)
Endogenous proteolysis in chromatin of terminally differentiated, quiescent, and actively proliferating cells was studied by measuring the released acid-soluble radioactivity of [3H]tryptophan-prelabelled nuclear proteins, and by following the specific quantitative and qualitative changes in electrophoregrams of chromosomal proteins. The experiments suggest(More)
In contrast to the widely accepted idea of the nearly absolute metabolic stability of histones, our experiments support the view that the histones of nonproliferating, terminally differentiated cells undergo continuous replacement. This conclusion is based on the incorporation of labeled amino acids into the histones of mouse kidney and liver cells after(More)
This study examines the turnover of the core histones in proliferating Friend cells. It was calculated that these proteins turn over with half-lives of 21.6 days for H2A, 13.8 days for H2B, 43.3 days for H3, and 138.6 days for H4. The significant differences in the half-lives of the four core histones indicate that the protein moiety of the nucleosome is(More)
The pulse-chase experiments with Friend erythroleukemia cells designed to reveal the metabolic properties of the protein complex of 40-S particles showed that the major polypeptides of this complex turn over with half-lives between 19 h and 206 h. the main conclusion from the experiments is that the complex does not degrade as a single unit. Since the(More)
The presence of DNA topoisomerase IIalpha was investigated in interphase and metaphase mouse erythroleukemia (MEL) Friend-S cells, and in extracted with 25 mM lithium diiodosalicylate buffer (Lis) nuclei using indirect immunofluorescence. The results showed that DNA topoisomerase IIalpha is localised in the nuclei. In the metaphase cells, we found high(More)
1. Qualitative and quantitative distribution of the non-histone proteins in nuclear matrix, chromatin, a new type of RNP-network and nucleosol of Friend cells have been investigated. 2. The specific territorial distribution and metabolism of these proteins found support for the idea of their exact compartmentalization. 3. Since the majority of the(More)