| FLP from Saccharomyces cerevisiae, a site-specific recombinases (SSR) from the i integrase family, recognizes distinct 34 bp FRT sites. It has been widely used for generating conditional knockout mice, mediated by FLP/FRT system. Initial use of FLP in mammalian cells revealed inefficient recombinase activity due to thermo-instability of the FLP protein. Subsequent screening for thermo-stable mutants resulted in the identification of FLPe, with a 4-fold increase in recombination efficiency at 37C. However the recombination efficiency of FLPe in cells remains very low because of its non-mammalian origin. FLPo is a mouse codon optimized FLPe that greatly increases the FRT recombination efficiency for both in vivo and in vitro in mouse. This adenovirus express FLPo under a control of a CMV promoter. |
