Fig. S1.

Synthesis primed from ends with an unpaired 3′ terminus. The G3′ substrate (described in cartoon) was introduced into MEFs as described in Fig. 1B, except using a panel of MEFs generated independently, derived from mice from different litters. Joining efficiency was determined by qPCR as in Fig. 1B. The proportion of recovered junctions formed after synthesis of a single complementary base (+C junction recovery) was approximated here by assessing the fraction of products sensitive to a restriction enzyme specific for this junction (NsiI). Error bars reflect the range of means from two triplicate transfections, performed on different days. ND, not detectable (recovery efficiency < 0.01).