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. Author manuscript; available in PMC: 2015 May 13.
Published in final edited form as: FEBS Lett. 2012 Jan 28;586(14):1906–1912. doi: 10.1016/j.febslet.2012.01.041

Figure 1. MiRNA Biogenesis Pathway.

Figure 1

Biosynthesis of miRNAs begins in the nucleus with the transcription of miRNA genes by RNA Pol II as long transcripts bearing a 7 methyl-guanosine cap at the 5′-end and a poly(A) tail at the 3′-end. The Drosha microprocessor complex, the minimal components of which are DGCR8 and Drosha, cleaves the pri-miRNA into pre-miRNA. Exportin 5 then exports the pre-miRNA into the cytoplasm where it undergoes a secondary processingstep into a short miRNA duplex by Dicer. The miRNA duplex contains both a mature miRNAstrand and a miRNA* strand. The mature miRNAis loaded into Ago proteins and mediates the silencing function as a part of the RISC, while the miRNA* gets degraded.