Figure 3.

CRISPR-Cas9 regulates gene expression. The designed small CRISPR RNAs with the Cas9 protein subsequently searches for the Cas-specific sequence. Upon recognition of the specific sequence, Cas9 induces the targeted double strand break, initiating the homologous directed repair. The CRISPR targeting specificity is determined both by CRISPR RNAs and the binding between the Cas9 protein; and a short DNA motif commonly found at the 3' end of the target DNA, called the PAM. PAM, protospacer adjacent motif.