Fig. 8.

RNA exonuclease activity in the presence of CDP-choline. (A) An RNA exonuclease assay was performed using 5′-³²P-labeled RNA with no enzyme (lanes 1 to 3) and with 6.28 milliunits of wt CDP-Chase (lanes 4 to 24) either in the absence (lanes 4 to 10) or the presence of 5 mM (lanes 11 to 17) or 10 mM (lanes 18 to 24) CDP-choline. Results at the 0-, 20-, and 60-min time points are shown for the no-enzyme control, and results at the 1-, 2-, 5-, 10-, 20-, 30-, and 60-min time points are shown for assays with enzyme. (B) The fraction of 43-nucleotide RNA remaining at 20 min is plotted for the no-enzyme control, the wt CDP-Chase, and the wt CDP-Chase in the presence of 5 mM and 10 mM CDP-choline.