Fig. 7.

Schematic of recombinase-mediate integration with mutant loxP sites schematic. As the reversible recombinase Cre results in an unstable configuration upon integration, use of loxP recognition sites with half site mutations (red arrow with yellow star) have been exploited. The half site mutations allow integration to occur at approximately wild type rates due to cooperative binding of the recombinase to the recognition site. Once recombined and both half site mutation are brought together future recombination events (excision) are inhibited thereby trapping the integration event. This is believed to be due to the loss of cooperative binding. Transient expression of the reversible recombinase further enhances the effectiveness of trapping of the integrated DNA—not shown