Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.474041
Title: Possible RNA processing enzymes in HeLa cell nuclei
Author: Strachan, T.
ISNI:       0000 0001 3488 0032
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1979
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Abstract:
1. HnRNP particles were isolated from monolayer cultures of HeLa cells and characterized with respect to their sedimentation in sucrose density gradients (s values from 0 to>250s)5 their buoyant density in CsC1 density gradients following aldehyde fixation of the particles (1.390 g.cm-3), their heterogeneous complement of polypeptides as analysed on SDS-polyacrylamide gels (species from 38,000 to >150,000 daltons) and the heterogeneous sedimentation of their rapidly labelled RNA component (s values from 0 to >40s). 2. Various potential RNA processing enzyme activities were investigated in relation to their possible association with HeLa hnRNP particles or related subnuclear fractions of chromatin and nucleosol. (a) Exoribonuclease activity which was dependent on Mg2+ ions was found to be largely confined to a nucleosol frciction and, to a lesser extent, to the chromatin fraction. No exoribonuclease activity could be detected in association with HeLa hnRNP par ticles. (b) Endoribonuclease activity of poor substrate specificity was detected in association with HeLa hnRNP particles, chromatin and nucleosol fractions. The hnRNP particle-associated activity was stimulated by Mg2+ but did not appear to be strictly dependent on the presence of Mg2+. The same activity permitted degradation of HeLa hnRNA to molecular species of lower average sedimentation coefficient than present in mRNA but without any accompanying production of acid-soluble components. (c) No double-strand RNA-specific RNase activity could be detected in association with HeLa hnRNP particles. Instead such activity appeared to be largely confined to the nucleosol fraction. (d) RNA guanylyItransferase activity could not be detected in association with HeLa hnRNP particles. Again such activity appeared to be confined to the nucleosol fraction. (e) RNA ligase activity similar to the bacteriophage T4 activity could not be detected in any of the HeLa subnuclear fractions tested, (f) No poly A synthetase activity could be detected in association with HeLa hnRNP particles. Rather, such activity was prominent in a HeLa nucleosol fraction and, to a lesser extent, in the corresponding chromatin fraction. The nucleosol-located activity was optimally stimulated in the presence of a poly A primer and appeared to be more dependent on the presence of exogenously provided RNA primer than the corresponding chromatin-associated activity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.474041  DOI: Not available
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