Figure 3.

ApeTpt1 caps RNA or DNA 5′-phosphate ends with ADP-ribose. Reaction mixtures (10 μl) containing 100 mM Tris–HCl (pH 7.5), 0.2 μM (2 pmol) 5′ ³²P-labeled 10-mer pDNA or pRNA substrates (shown at bottom), 1 mM NAD⁺ (where indicated by +), and 0.5 μM (5 pmol) ApeTpt1 (where indicated by +) were incubated at 37°C for 60 min. The reaction mixtures were heated at 65°C for 5 min and then either treated with calf intestine alkaline phosphatase (CIP +) or mock- treated (CIP –) as described in Figure 2. The products were analyzed by urea-PAGE and visualized by autoradiography.