B3R corresponds to the recombinase encoded by gene A of the Zygosaccharomyces bisporus pSB3 plasmid. It specifically recognizes the B3RT target site, with recombination occurring between a pair of these sites. The recombination event results in genetic modification, the nature of which is influenced by the relative orientation (direct or inverted), location and composition of the two recognition sites. The types of possible modification include deletion of DNA, generation of chromosomal rearrangements and integration of DNA into the genome. B3R shows low toxicity in transgenic Drosophila (FBrf0214794).
