Bacteriophage phiC31 integrase mediated transgenesis in Xenopus laevis for protein expression at endogenous levels

Bacteriophage phiC31 inserts its genome into that of its host bacterium via the integrase enzyme which catalyzes recombination between a phage attachment site (attP) and a bacterial attachment site (attB). Integrase requires no accessory factors, has a high efficiency of recombination, and does not need perfect sequence fidelity for recognition and recombination between these attachment sites. These imperfect attachment sites, or pseudo-attachment sites, are present in many organisms and have been used to insert transgenes in a variety of species. Here we describe the phiC31 integrase approach to make transgenic Xenopus laevis embryos.