Fig. 1.

Synthesis primed from ends with an unpaired 3′ terminus. (A) Description of the extrachromosomal DSB repair assay. (B) The G3′ substrate (described in cartoon) was introduced into the noted fibroblast cell lines. For each cell line, the efficiency of recovery for junctions formed after addition of a single complementary nucleotide (+C junction recovery) is expressed as a fraction of the total junctions recovered from WT cells. Error bars reflect the range of means from two triplicate transfections, performed on different days. Mean recovery efficiencies were assessed as significantly different with confidence P < 0.05 (*) or not significantly different (ns). (C) The percentage of junctions formed after accurate synthesis was determined after introduction into the Polm^−/−Poll^−/− cell line of GCG3′ substrate together with 0, 1, 10, 100, or 1,000 ng of Pol μ. The means and error bars were determined as in B.