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Fig. 1 | Journal of Experimental & Clinical Cancer Research

Fig. 1

From: Description of CRISPR/Cas9 development and its prospect in hepatocellular carcinoma treatment

Fig. 1

Mechanism of CRISPR/Cas9 gene editing tool. Viral or plasmid DNA would be processed into protospacers and integrated into repeat sequences to form the CRISPR array through Cas1,Cas2 and Csn2. Typical CRISPR locus (from Streptococcus pyogenes) consists of tracrRNA sequence, several Cas genes, leader sequence and CRISPR array. CRISPR array transcribes into pre-crRNA. The tracrRNA combines pre-crRNA to form a mature tracrRNA-crRNA complex processed by nucleases. During exogenous gene interference, this complex activates Cas9 endonuclease and recognizes a 20-nt crRNA complementary sequence within exogenous gene, while Cas9 finds PAMs. The double-stranded DNA would be cleaved at 3 nt upstream of the PAMs ultimately by Cas9 endonuclease. Abbreviations: crRNA, CRISPR RNA; tracrRNA, trans-activating crRNA; pre-crRNA, crRNA precursor; PAMs, protospacer adjacent motifs

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