Some diagrams show that they are different. However, some explanations say that they are the same. Is it different among species? If it is, why should there be a Dicer in the RISC, or that a Dicer be separate from the RISC?
Hi,
In gene silencing (RNAi), Dicer (RNase III) facilitates the cleavage of ds RNA molecules to siRNA. These siRNA fragments goes on and guide the cleavage of mRNA in P bodies with the help of RISC. Argonaute protein (slicer) is responsible for cleavage for mRNA cleavage.
Dear Manimar
As I know, Dicer is responsible for dsRNA detection and cleavage. However, it not alone in this recognition and cleavage process. After cleavage, Dicer delivers the cleaved small dsRNAs to RISC accompanied by other proteins. Therefore, Dicer is not a member of RISC.
I have reviewed the details of RNAi involved molecular process in several model organisms including C. elegans, Arabidopsis thaliana, Drosophila and also in Humans. The links below may help you more.
Article Human RNAi Pathway: crosstalk with organelles and cells
Article Reconstruction of Arabidopsis thaliana fully integrated smal...
Article RNAi pathway integration in Caenorhabditis elegans development
Hi Manimar
Both Dicers are the same in higher eukaryotes (human and mammals). In plants and lower eukaryotes as fungi, it is common to find Dicer isoforms. As far as I know, there is no evidence of the existence of a specific Dicer isoform to cleave the dsRNAs and another one to engage the RISC.
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