Dicer

Dicer is an endoribonuclease in the RNase III family that cleaves double-stranded RNA (dsRNA) and pre-microRNA (miRNA) into short double-stranded RNA fragments called small interfering RNA (siRNA) about 20-25 nucleotides long, usually with a two-base overhang on the 3' end. Dicer contains two RNase III domains and one PAZ domain; the distance between these two regions of the molecule is determined by the length and angle of the connector helix and may influence the length of the siRNAs it produces. Dicers interact with several partner proteins (TRBP in humans, R2D2, Loqs in Drosophila). These partner proteins could play a role in dictating the substrate specificity of Dicer proteins.