Cre: Proteins and Enzymes

The Cre (cyclization recombination) enzyme, a member of a large family of recombinases, recognizes loxP which is a sequence motif of 34 bp from the PI bateriophage. If a DNA seqment is flanked by two loxP sites in the same orientation, Cre excises that seqment leaving a single loxP site in the remaining DNA molecule. The excised DNA segment is subsequently degraded. Cre and lox comprise the Cre/lox system which was first developed in the late 1980's to artificially manipulate gene expression (reviewed in Branda and Dymecki, 2004; Ghosh and Duyne, 2002; and Gilbertson, 2003). As an example, mice with the Cre protein expressing in a specific cell type are bred with mice that contain a target gene surrounded by loxP sites. When the mice are bred, the cells carrying Cre will cause those cells to lose the target gene. If the Cre gene is, for example, bound to a promoter that only allows Cre production in neuronal cells, the target gene will be deleted only in those cells. Since 1989 the Cre/lox system has been used extensively and there are numerous animal, plant and bacterial stocks that already contain the Cre gene driven by ubiquitous, tissue-specific or inducible promoters and provide a quick method for breeding experiments. The Cre/lox system has the advantage of working in almost any type of cell. This has led to its application in many experiments, for example in selectively labeling neuronal cells in the brain thereby differentiating them from other types of surrounding cells. This Cre antibody recognizes the recombinase protein, Cre. Cre is a 343 amino acid protein, GenBank no. AAQ14086.1.