Figure 2.

Anatomy of a miRNA. The miR-132-3p canonical sequence targets several sites within the DNMT3A-3′ UTR, including the one shown (interaction predicted by miRbase). Targeting is mostly dictated by the seed sequence (shaded in blue) within the miRNA: nucleotides 2-7 or 2-8 (5′ to 3′). Additional targeting can occur within the 3′ supplementary region (shaded in pink), which is separated from the seed sequence by a noncomplementary linker sequence. The linker sequence varies in length, depending on the target and the position of the 3′ supplementary region. The final nucleotides near the 3′ end of the miRNA form the miRNA’s 3′ tail. The 3′ tail rarely contributes to mRNA targeting but undergoes frequent editing by exonucleases, which trim the miRNA, and nucleotidyl transferases, which add nucleotides to the tail of the miRNA.