Eukaryotes silence gene expression in the presence of double-stranded RNA homologous to the silenced gene. Silencing occurs by the targeted degradation of mRNA. Biochemical reactions that recapitulate this phenomenon generate RNA fragments of 21-23 nucleotides from the double-stranded RNA. These stably associate with an RNA endonuclease and probably serve as a discriminator to select mRNAs. Once selected, mRNAs are cleaved at sites 21-23 nucleotides apart. This mechanism, termed RNAi, has functional links to viral defense and silencing phenomena, such as cosuppression. It also functions to repress the hopping of transposable elements.
ASJC Scopus subject areas
- Cell Biology