title: In vitro inhibition of HeLa cell nuclear ribonucleases by ADP-ribosylation.
abstract: Ribonuclease activity in HeLa cell nuclei is markedly inhibited by ADP-ribosylation following incubation of intact isolated nuclei with [14C]NAD. Time course experiments demonstrate that [14C] incorporation into proteins is accompanied by a 50% inhibition of ribonuclease activity on single-strand and double-strand polynucleotides. Inhibition does not occur when 3-aminobenzamide, a potent (ADP-ribose) polymerase inhibitor, is present. Two enzymatic activities that degrade double-strand polynucleotides have been purified and partially characterized. A relevant level of radioactivity resulting from [14C]NAD incubation of nuclei was associated to the purified enzyme. The RNase F1 component, which shows maximal activity on polyU-polyA is demonstrated to be the major ADP-ribose acceptor protein.
authors.affiliation: Department of Organic and Biological Chemistry, University of Naples, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Quesada
authors.forename: M
authors.initials: M
authors.lastname: Merola
authors.forename: B
authors.initials: B
authors.lastname: Farina
authors.forename: E
authors.initials: E
authors.lastname: Leone
mesh_terms: D002467:Cell Nucleus / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D011065:Poly(ADP-ribose) Polymerases; D012260:Ribonucleases