Top Questions

There are no NGG PAM sequences close to my locus of interest. What can I do?

If the region of interest is so narrow that there are no “GG” motifs, you may have to explore Cas endonucleases from other organisms that recognize different PAM sites.

Jiang et al. have shown that S. pyogenes Cas9 also recognizes another PAM site: NAG, though with lesser efficiency than NGG [1].

Alternatively, for T-rich sequences, the Cpf1 system may be of utility, as it recognizes a TTTV PAM site, where V is A, C, or G. IDT offers the Alt-R® Cpf1 System (crRNA, nuclease, and electroporation enhancer), which is beneficial for editing around T-rich sequences. Visit the Alt-R Cpf1 System webpage for more information, or contact us at to discuss what we have learned in our ongoing research.


  1. Jiang W, Bikard D, et al. (2013) RNA-guided editing of bacterial genomes using CRISPR-Cas systems. Nat Biotech, 31:233–239.
  • Cpf1
  • Cas9
  • PAM
  • Alt-R
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