MicroRNAs are short, non-coding RNA molecules complementary to mRNA molecules. By binding to mRNAs in the cytoplasm, microRNAs are able to post-transcriptionally control protein expression, typically by binding to the mRNA at the 3’ UTR.
On the binding of the microRNA, an RNA-induced silencing complex cleave the target mRNA, recruiting deadenylases leading to the subsequent repression of translation.