Ribonuclease III, Nuclear (RNASEN)

Members of the ribonuclease III superfamily of double-stranded (ds) RNA-specific endoribonucleases participate in diverse RNA maturation and decay pathways in eukaryotic and prokaryotic cells. The RNase III Drosha is the core nuclease that executes the initiation step of microRNA (miRNA) processing in the nucleus. Wu et al. (2000) found that the expressed purified RNase III domain cleaves double-stranded, but not single-stranded, RNA. They observed that the gene was ubiquitously expressed in human tissues and cell lines and that the protein is localized in the cell nucleus. Levels of transcription and translation of the RNase III protein did not change during different phases of the cell cycle. However, a significant fraction of the protein in the nucleus was translocated to the nucleolus during the S phase of the cell cycle.