I've read a book describing Cre-Loxp system (see the diagram). I am wondering does Cre only cut homozygous floxed allele but not heterozygous one? Thanks for answering.
Hi Chen,
Cre-mediated deletion will occur on any allele so long as there are flanking LoxP sites in the same orientation (right side of diagram). If both alleles of "Gene X" possess flanking LoxP sites, then both alleles will be deleted (homozygous deletion). If only one allele, has the LoxP sites, then only THAT allele gets deleted (heterozygous deletion). PCR of genomic DNA using appropriately designed primer sequences will tell you whether or not your gene of interest is targeted for homozygous or heterozygous deletion.
Agree to Peter, just to add more information:
First, Cre cut the target as long as it's floxed, so het will have one copy cut while hom both copies cut.
Second, in many papers people found out that the excision efficiency by Cre is less than 70%, sometimes less than 50%, but as long as it's sufficient for your phenotype in your context it's fine.
Third, then people like the idea cross fl/fl homozygous mouse with KO mouse in the same gene to create fl/- so that even though the cutting is not 100% but by having one copying knocked out it can lead to no less than 50% cutting efficiency, which should be better than fl/fl.
Forth, once it's cut, people use qPCR to check the mRNA level of that gene in certain type of cells or all cells, and the protein level by FACS of western blot.
- Badges
- Science topic
- Similar topics
- Biological Science
- Anatomy
- Tissue