Cre-Recombinase is a site-specific DNA recombinase derived from bacteriophage P1. It is highly specific for a 34 bp DNA sequence (loxP) found in P1 DNA and catalyzes site-specific recombination between two 34-base-pair LOXP recognition sites, enabling precise deletion, inversion, or activation of DNA sequences. Its role is to maintain the phage genome as a monomeric unit-copy plasmid in the lysogenic state [1].
In experimental biology, Cre is commonly expressed under tissue-, cell-, or temporally specific promoters, allowing conditional manipulation of genes in transgenic and knockout mouse models [2, 3]. Inducible variants such as Cre-ERT are fused to a modified estrogen receptor domain and can be activated by tamoxifen, providing temporal control of recombination [4].