Dicer, also known as Dicer1, endoribonuclease Dicer, Helicase with RNase motif is a member of the RNase III family. It contains a N-terminal DEXH-box RNA helicase/ ATPase domain, followed by a domain of unknown function (DUF283), a Piwi/Argonaut/Zwill (PAZ ) domain, which anchors the 3′-end of RNA substrates.
Dicer catalyzes the first step in the RNA interference (RNAi) pathway and initiates formation of the RNA-induced silencing complex (RISC). Dicer processes the dsRNA into small fragments called short interfering RNA (siRNA) or microRNA (miRNA) of typically 21-25 nucleotides long with a two-base overhang on the 3′. It helps to load these fragments into the RNA-induced silencing complex (RISC), which guides the sequence-specific silencing of mRNAs that contain complementary sequences by either enzymatically cleaving the mRNA or repressing its translation.
