In contrast, when base pairing between miRNA and target mRNA is imperfect, the interaction of the miRNP complex with the target mRNA results in translation repression (Doench et al, 2003).
Thus, the Piwi mutations affect repression by perfect and imperfect miRNA interactions alike.
This imperfect base-pairing interaction of miRNAs with their target sites hampers the identification of regulated genes.
The miRNAs are endogenous small non-coding RNAs that regulate gene expression by promoting mRNA degradation or preventing translation by imperfect sequence-specific interaction with the 3′-untranslated region of mRNAs.
Recently implicated directly in cancer initiation and/or progression using mouse models (reviewed in [39]), microRNAs regulate gene expression usually through imperfect base-pairing interactions with the 3' UTR of its target mRNAs leading to mRNA degradation and/or translational inhibition.
These include causal interactions, imperfect experiments, adjustment for confounding, time-varying exposures, competing risks and the probability of causation.
In animals, miRNAs generally inhibit translation of their target genes through imperfect base-pairing interactions, mostly in the 3′ untranslated regions (UTRs) of transcripts.
Trans-encoded sRNAs form imperfect base-pairing interactions with complementary sequences in their mRNA targets, which are often located at or near ribosome binding sites (RBS), but can also be located upstream of the translation start site as well as deep in the coding regions (CDS) [ 2].
At the first stage DN and AAN physically join into an unstable (imperfect) "triplet" via stacking interaction between AAN and the 2nd nucleotide of DN, as well as via specific interaction of amino acid with DN (Fig. 1a).
Comparisons to parasite-host/predator-prey interactions are imperfect, but based on the rich literature of both interactions, they allow drawing testable predictions.
