non-coding RNA miRNA Small, ~22-nt, RNA molecule that is the endogenous transcript of a miRNA gene (or the product of other non coding RNA genes. Micro RNAs are produced from precursor molecules (SO:0000647) that can form local hairpin structures, which ordinarily are processed (usually via the Dicer pathway) such that a single miRNA molecule accumulates from one arm of a hairpin precursor molecule. Micro RNAs may trigger the cleavage of their target molecules or act as translational repressors. http://en.wikipedia.org/wiki/MiRNA http://en.wikipedia.org/wiki/StRNA micro RNA microRNA small temporal RNA stRNA Removed axiom 'derives_from some miRNA_primary_transcript' pending review of status of SO terms. Changed relation of small regulatory ncRNA (superclass) into is about relationship small_regulatory_ncRNA