Figure 4.
Integration frequency assays for shuffled integrases in human cells. (A) Quantitative PCR assay for integration frequency at ψA. Human 293 cells were transfected with pHZ-attB and either no integrase, the wild-type φC31 integrase, or one of 11 cycle 2 shuffled integrases, 1C2–11C2. After 2 days, genomic DNA was prepared and analyzed with probes specific for the ψA site with quantitative PCR. The absolute frequency of integration in the sample is shown, uncorrected for transfection efficiency. (B) Selection assay for total integration frequency. The number of hygromycin-resistant colonies generated by each integrase after co-transfection with pHZ-attB into 293 cells. Error bars in (A) and (B) represent the standard error.