NgAgo is a single-stranded DNA (ssDNA)-guided Argonaute endonuclease, an acronym for Natronobacterium gregoryi Argonaute. NgAgo binds 5′ phosphorylated ssDNA of ~24 nucleotides (gDNA) to guide it to its target site and will make DNA double-strand breaks at the gDNA site. Like the CRISPR/Cas system, NgAgo was reported to be suitable for genome editing, but this has not been replicated. In contrast to Cas9, the NgAgo–gDNA system does not require a protospacer adjacent motif (PAM).