Fig. 1
From: CRISPR/Cas9 system in breast cancer therapy: advancement, limitations and future scope
A Components of the CRISPR/Cas9 system: (i) Cas9 endonuclease which is responsible for cleavage of target DNA sequence, (ii) single guide (sg) RNA formed by the fusion of crRNA and tra-crRNA chimera, iii) protospacer adjacent motif (PAM) sequence required for Cas binding present in the target DNA sequence. B Cas9 protein is a bi-lobed structure consisting of the alpha lobe and the nuclease lobe. The nuclease lobe has two domains the HNH domain and RuvC domain which cleaves the complementary and the non-complementary strands of DNA respectively. Mutation at D10A in the RuvC domain and H840A of the HNH domain leads to the inactivation of Cas9 (dCas9). C Gene editing; Cas9-sgRNA complex targets the respective gene and causes double-strand breaks (DSBs) close to the PAM region. The damaged DNA is repaired either by non-homologous end joining (NHEJ) or the homologous DNA repair (HDR) pathway