Site-specific recombination by the bacteriophage P1 lox-Cre system. Cre-mediated synapsis of two lox sites

The bacteriophage P1-encoded recombinase Cre forms a simple DNA-protein complex at the specific recognition site loxP. Furthermore, Cre is able to mediate a synaptic union of two loxP sites. When two loxP sites are on the same linear DNA molecule, Cre binds the two sites together to form a circular protein-DNA complex. These complexes can be resolved into a linear DNA molecule and a closed circular DNA molecule, the end products of site-specific recombination.