Hello, I have a doubt about the cre loxP system.Can the Cre recombinase catalyse the excision of the fragment between the loxP sites on an episomal substrate, for example, a plasmid that has not been integrated in genomic DNA yet?
Yes. People have been using them for 'transient' assay. We have been co-transfering 'loxP-stuffer-loxP' plasmid and Cre-expressing plasmid into bacteria, yeast and tobacco protoplasts for experiments and obtain positive results (DNA fragment between two loxP sites was removed.).