complex. This act as guide RNA for cas9 protein directing it for its endonuclease activity. RNA mutagenesis One important gene regulation method is RNA mutagenesis which can be introduced by RNA editing with the help of gRNA. Guide RNA replaces adenosine with inosine at the specific target site and modify the genetic code. Adenosine deaminase acts on RNA bringing post transcriptional modification by altering the codons and different protein functions. Guide RNAs are the small nucleolar RNA, these along with riboproteins perform intracellular RNA alterations such as ribomethylation in rRNA and introduction of pseudouridine in preribosomal RNA. Guide RNAs binds to the anti sense RNA sequence and regulates the RNA modification. It is observed that small interfering RNA (siRNA) and micro RNA (miRNA) are generally used as target RNA sequence and modifications are comparatively easy to introduce because of small size. See also CRISPR gene editing CRISPR/Cas Tools SiRNA Gene knockout Protospacer adjacent motif References Further reading Guide RNA-directed uridine insertion RNA editing in vitrohttp://www.jbc.org/content/272/7/4212.full Genome editing RNA