micrornas（micrornas）是短的（20-24nt）非編碼RNAs，通過影響mRNas的穩定性和翻譯，參與多細胞生物中基因表達的轉錄后調控。小RNA被RNA聚合酶II轉錄，作為可編碼蛋白質或不編碼的有帽和多聚腺苷酸化的初級轉錄物（pri-mirnas）的一部分。初級轉錄物被Drosha核糖核酸酶III酶切割，產生一個大約70 nt的干環前體小RNA（前小RNA），然后被細胞質骰子核糖核酸酶進一步切割，產生成熟的小RNA和反義的小RNA星（小RNA*）產物。成熟的小RNA被整合到一個RNA誘導的沉默復合物（RISC）中，該復合物通過與小RNA的不完全堿基配對識別目標mRNAs，最常見的結果是對目標mRNa的翻譯抑制或失穩。refseq代表預測的microRNA干環。
microRNAs (miRNAs) are short (20-24 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression 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 primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transcript is cleaved by the Drosha ribonuclease III enzyme to produce an approximately 70-nt stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic Dicer ribonuclease to generate the mature miRNA and antisense miRNA star (miRNA*) products. The mature miRNA is incorporated into a RNA-induced silencing complex (RISC), which recognizes target mRNAs through imperfect base pairing with the miRNA and most commonly results in translational inhibition or destabilization of the target mRNA. The RefSeq represents the predicted microRNA stem-loop.