Figure 5.

Ddk1 can act in both directions. (A) Ddk1 activity was assayed using 5′- or 3′-labelled single-stranded 44DNA substrate and (B) 5′ 44RNA–DNA, 44DNA–RNA chimeric substrates and 44DNA, 44RNA substrates. Dashed rectangle marks the region of the gel subjected to quantitative analysis (graph, right). An RNA ladder and a reference RNA fragment (22RNA) were also resolved. (A and B) Reactions were performed in standard conditions using indicated amounts of the enzyme for indicated times. Products were resolved using 20 (A) or 15% (B) urea–PAGE.