Micro RNA (miRNA) is a type of non-coding RNA (ncRNA). miRNA molecules are about 22 nucleotides in length and are initially transcribed as a longer hairpin-structured precursor primary miRNA transcript (pri-miRNA) which is more than 1000 nucleotides long. miRNA are involved in the post-transcriptional regulation of gene expression and they typically interact with specific mRNAs through complementary base-pairing to influence the translation or stability of the target messenger RNA (mRNA) molecule.
miRNA works by binding to target mRNAs through complementary base-pairing, resulting in translation supression and gene silencing. They are found in all eukaryotic cells.
miRNAs can be described as “multivalent,” with one miRNA able to target multiple genes, thus regulating the expression of several proteins, whereas siRNA inhibit the expression of one specific target mRNA.
The post-transcriptional regulation is the control of gene expression at the RNA level. Control of the gene expression is between the transcription and translation of the gene.