Skip to main content
. Author manuscript; available in PMC: 2011 Dec 27.
Published in final edited form as: Nature. 2009 Jan 22;457(7228):413–420. doi: 10.1038/nature07756

Figure 1. Pathways of RNA processing and biogenesis of small RNAs.

Figure 1

a, Generation of endogenous siRNAs from dsRNA resulting from convergent transcription (sense–antisense RNA base-pairing; top) or transcription through inverted repeat sequences (hairpin RNA formation; bottom). TER, transcription termination signal. b, Processing of non-coding and aberrant RNAs by the RDRC and TRAMP complexes, containing the Cid12 and Cid14 non-canonical polyadenylation polymerases, respectively; the RDRC/Dicer pathway produces duplex siRNAs, whereas the TRAMP/exosome pathway produces single-stranded degradation products. c, Generation of a free 3′ end by the slicer activity of an Argonaute protein, which can be processed into dsRNA by RdRP or targeted for degradation by the exosome (not shown). d, Pathway for the generation of piRNAs by the PIWI clade of Argonaute proteins: PIWI, AUB and AGO3.