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. 2007 Jan-Mar;3(1):25–33. doi: 10.4161/org.3.1.3670

Figure 1.

Figure 1

MicroRNA biogenesis. MiRNAs are mainly derived from RNA polymerase II transcribed genes. The primary transcript (pri-microRNA) is often polycistronic, containing several miRNas. In the nucleus, Drosha in conjunction with DRCG8 processes the pri-microRNAs into pre-microRNAs that are exported to the cytoplasm by Exportin5. In the cytoplasm, the mature miRNA is formed by the enzymatic activity of Dicer. The mature miRNAs is incorporated or “loaded” into the RISC (star shaped icon) that mediates miRNA-directed targeting of specific mRNAs.