Molecular model showing CRISPR-Cas12j protein complexed to a ribonucleic acid (RNA, orange) strand and a DNA (deoxyribonucleic acid) strand that has been cut into two pieces (green and blue). CRISPR-Cas protein complexes are used in genome engineering to cut DNA (deoxyribonucleic acid). The system uses a guide RNA sequence to cut DNA at a complementary cleavage site. CRISPR Cas-12j is a Cas protein found in bacteriophages, that can cut double stranded DNA. Cas-12j is currently the smallest Cas protein to be discovered with a molecular weight about half of the Cas9 protein, which was discovered in bacteria and now used in genetic engineering to cut DNA. Cas12j's small size gives it an advantage over Cas9 for use in gene editing because it allows for easier delivery into cells by a viral vector.