The phiC31:Dint(HEG) entry in FlyBase represents an engineered variant of the integrase encoded by the phiC31 bacteriophage, which has been mutated so that it shows atypical recombination properties relative to the wild-type phiC31:int integrase; phiC31:Dint(HEG) shows a high-level of 'excisionase' or 'disintegrase' activity in vivo, that is, it can catalyze recombination between an attL and an attR site (the hybrid sites that are normally created when wild-type phiC31:int is used to drive recombination between an attB and an attP site). phiC31:Dint(HEG) can thus be used to regenerate a functional attP 'landing' site from a previously integrated transgene that contains an attL/attR pair. phiC31:Dint(HEG) carries E339H and E463G substitutions relative to the wild-type integrase (FBrf0228049).