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. [provided by RefSeq, Sep 2009]. Sequence Note: This record represents a predicted microRNA stem-loop as defined by miRBase. Some sequence at the 5' and 3' ends may not be included in the intermediate precursor miRNA produced by Drosha cleavage.
The RefSeq Genes track shows known human protein-coding and
non-protein-coding genes taken from the NCBI RNA reference sequences
collection (RefSeq). The data underlying this track are updated weekly.
Please visit the Feedback for Gene and Reference Sequences (RefSeq) page to
make suggestions, submit additions and corrections, or ask for help concerning
For more information on the different gene tracks, see our Genes FAQ.
Display Conventions and Configuration
This track follows the display conventions for
gene prediction tracks.
The color shading indicates the level of review the RefSeq record has
undergone: predicted (light), provisional (medium), reviewed (dark).
The item labels and display colors of features within this track can be
configured through the controls at the top of the track description page.
- Label: By default, items are labeled by gene name. Click the
appropriate Label option to display the accession name instead of the gene
name, show both the gene and accession names, or turn off the label
- Codon coloring: This track contains an optional codon coloring
feature that allows users to quickly validate and compare gene predictions.
To display codon colors, select the genomic codons option from the
Color track by codons pull-down menu. For more information about this
feature, go to the
Coloring Gene Predictions and Annotations by Codon page.
- Hide non-coding genes: By default, both the protein-coding and
non-protein-coding genes are displayed. If you wish to see only the coding
genes, click this box.
RefSeq RNAs were aligned against the human genome using BLAT. Those
with an alignment of less than 15% were discarded. When a single RNA
aligned in multiple places, the alignment having the highest base identity
was identified. Only alignments having a base identity level within 0.1% of
the best and at least 96% base identity with the genomic sequence were kept.
This track was produced at UCSC from RNA sequence data generated by scientists
worldwide and curated by the NCBI
BLAT - the BLAST-like alignment tool.
Genome Res. 2002 Apr;12(4):656-64.
PMID: 11932250; PMC: PMC187518
Pruitt KD, Brown GR, Hiatt SM, Thibaud-Nissen F, Astashyn A, Ermolaeva O, Farrell CM, Hart J,
Landrum MJ, McGarvey KM et al.
RefSeq: an update on mammalian reference sequences.
Nucleic Acids Res. 2014 Jan;42(Database issue):D756-63.
PMID: 24259432; PMC: PMC3965018
Pruitt KD, Tatusova T, Maglott DR.
NCBI Reference Sequence (RefSeq): a curated non-redundant sequence database of genomes, transcripts and proteins.
Nucleic Acids Res. 2005 Jan 1;33(Database issue):D501-4.
PMID: 15608248; PMC: PMC539979