CRISPR-Cas12d belongs to the Type V CRISPR systems, where Cas12d (formerly known as CasY) is a Class II effector protein. The most widely known Class II effector protein, Cas9 in the Type II system binds and cleaves double-stranded DNA targets that match its guide crRNA and has been adapted as a genome editing tool. Cas12d is less well studied but has been shown to be capable of RNA-guided DNA targeting by demonstrating guide RNA-guided DNA interference activity. Cas12d, originally identified as CasY, was pulled out of a search through DNA sequencing data from uncultivated natural microbial communities . Cas12e (formerly CasX) was identified in this same study.