Influence of nucleotides, cations and nucleoside triphosphatase inhibitors on the release of ribonucleic acid from isolated rat liver nuclei

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Abstract
The reasons underlying reported discrepancies in the effects of ATP, ADP, adenosine 5''-[.beta..gamma.-methylene]triphosphate, AMP + PPi, p-chloromercuribenzoate and F- on RNA efflux from isolated rat liver nuclei and on nuclear-envelope nucleoside triphosphatase activity were investigated. The stimulatory effect of ADP was attributed to myokinase activity associated with the nuclei; this activity was eluted on repeated washing with nuclear incubation medium. In the absence of Ca2+ and Mn2+, ATP, adenosine 5''-[.beta..gamma.-methylene]triphosphate and AMP + PPi promoted release of DNA and RNA. In the presence of 0.5 mM-Ca2+ and 0.3 mM-Mn2+, only ATP promoted RNA efflux to a significant extent. In the absence of spermidine, Ca2+ and Mn2+, nuclei released large quantities of DNA and RNA into the medium; this effect was promoted by p-chloromercuribenzoate. In the presence of the 3 cations, p-chloromercuribenzoate inhibited RNA efflux. F- caused a slight leakage of DNA from nuclei. The results are discussed in terms of models for the effects of ATP and analogues on RNA efflux and nuclear stability.