What is the purpose of a PAM sequence in CRISPR-Cas systems?
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4 min read
In the widely used *Streptococcus pyogenes* CRISPR-Cas9 system, the Cas9 enzyme relies on a specific protospacer adjacent motif (PAM) sequence, typically 5′-NGG-3′, to correctly identify and modify target DNA. This short DNA sequence is essential for the CRISPR machinery to differentiate between the host's own genetic material and foreign, invading DNA, thereby enabling precise gene editing while preventing a self-inflicted attack.
