The<unk> /lox system is used as a genetic tool to control site specific<unk>  events in genomic DNA. This system has allowed researchers to manipulate a variety of genetically modified organisms to control gene expression, delete undesired DNA sequences and modify chromosome architecture.
The system begins with the<unk>  protein, a site-specific DNA recombinase.<unk>  can catalyse the<unk>  of DNA between specific sites in a DNA molecule. These sites, known as<unk> P sequences, contain specific binding sites for<unk>  that surround a directional core sequence where<unk>  can occur.
When cells that have<unk> P sites in their genome express<unk> , a reciprocal<unk>  event will occur between the<unk> P sites. The double stranded DNA is cut at both<unk> P sites by the<unk>  protein and then ligated (glued) back together. It is a quick and efficient process. The efficiency of<unk>  depends on the orientation of the<unk> P sites. For two<unk>  sites on the same chromosome arm, inverted<unk> P sites will cause an inversion, while a direct repeat of<unk> P sites will cause a deletion event. If<unk> P sites are on different chromosomes it is possible for translocation events to be catalysed by<unk>  induced<unk> .
The<unk>  (Cyclization<unk>  protein consists of 4 subunits and two domains  : The larger carboxyl (C-terminal) domain, and smaller amino (N-terminal) domain. The total protein has 343 amino acids. The C domain is similar in structure to the domain in the Integrase family of enzymes isolated from lambda phage. This is also the catalytic site of the enzyme.<unk>  P (locus of X-over P1) is a site on the Bacteriophage P1 consisting of 34 bp. There exists an asymmetric 8 bp sequence in between with two sets of palindromic, 13 bp sequences flanking it. The detailed structure is given below.
Cre-Lox recombination
Dimroth rearrangement
Self-replication
Mitotic crossover
Somatic hypermutation
Splicing 
Thermal depolymerization
Gene knockdown