Figure 3.

The biogenesis of miRNAs. A schematic depicting the biogenesis and function of a mature miRNA. Primary miRNA (pri-miRNA) is transcribed in the nucleus and processed by Drosha and DiGeorge syndrome critical region 8 (DGCR8). The precursor miRNA (pre-miRNA) is then exported by exportin-5 (EXP-5) out into the cytoplasm. Here, the pre-miRNA is further cleaved by Dicer to yield a double-stranded miRNA duplex. After strand selection, the mature miRNA associates with the RISC. The degree of complementarity between the miRNA and the target mRNA determines whether the mRNA is degraded or the translation process is blocked.