 conducted a DALI search in order to find similarities between other proteins, and they found no informative similarities.The principal function of anti-CRISPR proteins is to interact with specific components of CRISPR-Cas systems, such as the effector nucleases, to avoid the destruction of the phage DNA (by binding or cleavage).A phage introduces its DNA into a prokaryotic cell, usually the cell detects a sequence known as "target", that activates CRISPR-Cas immune system, but the presence of an initial sequence (before the target) encoding the formation of Acr proteins, avoids phage destruction.