double-stranded RNA binding motif of metazoan ribonuclease III (RNase III) and similar proteins
RNase III (EC 3.1.26.3; also known as Drosha, or ribonuclease 3) is a double-stranded RNA (dsRNA)-specific endoribonuclease that is involved in the initial step of microRNA (miRNA) biogenesis. It is a component of the microprocessor complex that is required to process primary miRNA transcripts (pri-miRNAs) to release precursor miRNA (pre-miRNA) in the nucleus. Within the microprocessor complex, RNase III cleaves the 3' and 5' strands of a stem-loop in pri-miRNAs (processing center 11 bp from the dsRNA-ssRNA junction) to release hairpin-shaped pre-miRNAs that are subsequently cut by the cytoplasmic DICER to generate mature miRNAs. It is also involved in pre-rRNA processing. Metazoan RNase III is a larger protein than bacterial RNase III. It contains two RNase III domains in the C-terminal half of the protein followed by a double-stranded RNA binding motif (DSRM). DSRM is not sequence specific, but highly specific for dsRNAs of various origin and structure.
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