Crispr/cas9 System Knowledge base
CRISPR (clustered regularly interspaced short palindromic repeats) is a family of DNA sequences derived from viruses that have previously infected the prokaryotes and has the ability to recognize invasive homologous DNA sequences from similar viruses.
CRISPR/Cas9 system can be delivered in vitro by the non-viral reagents (such as polymer, liposome, nano-particle, electroporation) or viral vectors (such as lentivirus, adenovirus and AAV) and in vivo by adenovirus or AAV vectors.
The PAM sequence that SpCas9 recognizes is NGG (AGG, TGG, CGG, GGG), while SaCas9 recognizes NNGRRT (NNGAAT, NNGAGT, NNGGAT, NNGGGT) or NNGRRN. For sgRNA, the length is about 21 or 22 nucleotides.