MicroRNA 494 is a
microRNA sequence which is encoded in humans by the MIR494
gene.
Function
MicroRNAs (miRNAs) are short (20–24
nucleotides)
non-coding RNAs which are involved in
post-transcriptional regulation of
gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...
in multicellular organisms by affecting both the stability and translation of mRNAs. miRNAs are transcribed by
RNA polymerase II as part of capped and
polyadenylated
Polyadenylation is the addition of a poly(A) tail to an RNA transcript, typically a messenger RNA (mRNA). The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In euka ...
primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transcript is cleaved by the
Drosha ribonuclease III
Drosha is a Class 2 ribonuclease III enzyme that in humans is encoded by the ''DROSHA'' (formerly ''RNASEN'') gene. It is the primary nuclease that executes the initiation step of miRNA processing in the nucleus. It works closely with DGCR8 and i ...
enzyme to produce an approximately 70-nucleotide stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic
Dicer ribonuclease
Dicer, also known as endoribonuclease Dicer or helicase with RNase motif, is an enzyme that in humans is encoded by the gene. Being part of the RNase III family, Dicer cleaves double-stranded RNA (dsRNA) and pre-microRNA (pre-miRNA) into short d ...
to generate the mature miRNA and
antisense miRNA* ("mi-RNA star") products. The mature miRNA is incorporated into an
RNA-induced silencing complex (RISC), which recognises target miRNAs through imperfect base pairing with the miRNA and most commonly results in translational inhibition or destabilisation of the target mRNA. This RefSeq represents the predicted microRNA stem-loop.
References
Further reading
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