Figure 7. PARylation of cell extract proteins of NMR and mouse cells in presence of [32P]NAD+. (A) The activated DNA was incubated with 0.5 mg/ml of cell extracts of NMR cells (lanes 1 – 5) or mouse cell (lanes 6 – 10). The control probes (lanes 11–14) contained 70 nM PARP1 instead of cell extracts and 40 µM [32P]NAD+ (lanes 11 and 13) or 400 µM [32P]NAD+ (lanes 12 and 14). Lanes 13 and 14 correspond to lanes 11 and 12 but with low exposure. The reaction mixtures were incubated at 370C for 4 min. The mixtures were supplemented with loading buffer, heated at 970C for 10 min and then analyzed as described in the section ‘PARylation of cell extract proteins’. (B) Quantification showing the yield of PARylation products (A). Post-irradiation time is the time the cells were cultivated after irradiation before the cells were harvested for the following extract preparation. “n” designates non-irradiated cells.