microRNAs: Definition & Overview
MicroRNAs (miRNAs) are small, RNA molecules encoded in the genomes of plants and animals (Figure 1). These highly conserved, ~21-mer RNAs regulate the expression of genes by binding to the 3'-untranslated regions (3'-UTR) of specific mRNAs.
Figure 1. Transcription of miRNAs. Approximately 60% of miRNAs are expressed independently, 15% of miRNAs are expressed in clusters, and 25% are in introns.
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