Figure 7.
Proposed general mechanism depicting consequences of 3′ addition. Precursor miRNA is depicted with miRNA strands of the processed duplex colored in purple and orange and the hairpin region colored in gray. Formation of uridine tail in precursor miRNA blocks uptake into DICER1, while PAPD4-mediated adenylation of purple strand, predicted to be mediated at least in part by secondary structure character, selectively interferes with uptake into AGO proteins (interactions which are not thought to proceed are depicted with filled circles).
