CIBN::cre-C and CRY2::cre-N form the two halves of a photo-inducible split-Cre recombinase system. CRY2::cre-N consists of the Arabidopsis thaliana CRY2 gene (TAIR:28374) fused via a flexible linker to an N-terminal portion of the P1cre recombinase (amino acid residues 19-104). CIBN::cre-C consists of amino acid residues 1-170 of Arabidopsis thaliana CIB1 (TAIR:130033) fused via a flexible linker to a C-terminal portion of P1cre recombinase (amino acid residues 106-343). Both the CRY2 and CIBN fragments contain nuclear localization signals. In response to blue light, the CRY2 protein is activated and can dimerize with the CIBN peptide. This brings the two split 'cre-N' and 'cre-C' fragments together, reconstituting a functional P1cre recombinase (PMID:21037589). The reconstituted recombinase is expected to have the properties of the native P1cre recombinase, with compatible target sites corresponding to the wild-type loxP site and some of its derivatives. Recombination occurs between a pair of target sites oriented in the same direction; the 13bp repeats each act as binding sites for the recombinase, while the asymmetric 8bp spacer is the site of DNA strand exchange and determines the orientation of the target site (PMID:3856690). The recombination event catalyzed by the reconstituted recombinase results in genetic modification, the nature of which is influenced by the relative orientation (direct or inverted), location and composition of the two target sites. The types of possible modification include deletion of DNA and generation of chromosomal rearrangements (reviewed in FBrf0231034).