A protein derived from the CRISPR-Cas bacterial immune system that has been co-opted for genome engineering. Uses an RNA molecule as a guide to find a complementary DNA sequence. Once the target DNA is identified, Cas12 cuts both strands. Has been compared to “molecular scissors” or a “genetic scalpel.” In CRISPR immunity, cutting viral DNA prevents it from destroying the host cell. In genome engineering, cutting genomic DNA initiates a repair process that ends up making a change or “edit” to its sequence.
Note that Cpf1 (Cas12a), C2c1 (Cas12b), C2c3 (Cas12c), CasY (Cas12d), CasX (Cas12e), Cas14 (Cas12f), and CasPhi (Cas12j) are all Cas12 family members. Our illustration is based on Cas12a.