Figure 1.

RNAi Induced by siRNA

At the beginning of RNA interference process, through the activity of specific nucleases known as Dicers, siRNAs are transferred to specific ribonucleoprotein complexes referred to as RISCs. Transfer of siRNAs results in activation of RISCs, which, in turn, by means of an RNA helicase enzyme, induces unrolling of the double-stranded fragments. The antisense strand, in the next step, guides the RISC-siRNA complex to the complementary target mRNA. Finally, as the complex binds with the complementary mRNA, endonucleases in the RISC complex initiate the degradation process which is then continued by endonucleases in the cytosol, resulting in complete degradation of mRNAs complementary to the siRNA.