RNA splicing
Say it: ar-en-AY SPLY-sing
RNA splicing is the step in which introns are cut out of a newly made RNA and its exons are joined, producing a mature RNA ready for use.
Also: splicing, pre-mRNA splicing
Definition
What is RNA splicing?
In eukaryotes, most genes are first transcribed into a precursor RNA, or pre-mRNA, that still contains introns between the exons. RNA splicing removes those introns and stitches the exons together inside the nucleus, so the messenger RNA sent to the cytoplasm carries an unbroken coding sequence. Along with adding a 5' cap and a poly-A tail, splicing is one of the main steps of RNA processing.
The work is done by the spliceosome, a large complex of proteins and small nuclear RNAs (snRNAs). It recognizes the GU at the start of each intron and the AG at its end, cuts the RNA at both points and joins the neighboring exons. Precision matters: an error of a single base would shift the reading frame and spoil every codon downstream. A few unusual introns can cut themselves out without a spliceosome.
Through alternative splicing, a cell can include or skip particular exons, so a single gene can yield several different proteins, which helps explain the complexity of the human body. Mutations that disrupt splice sites are a well-known cause of genetic disease.
Word parts
Where does the term “RNA splicing” come from?
- splice
- to join rope ends by weaving their strands togetherMiddle Dutch splissen
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Where you'll meet it
Related
Terms that go with it
- IntronAn intron is a stretch of a gene that is copied into RNA but cut out by splicing before the RNA is used, so it does not code for protein.
- ExonAn exon is a section of a gene that stays in the final RNA after splicing removes the introns, and most exons carry code for protein.
- Messenger RNAMessenger RNA is the RNA copy of a gene that carries protein-building instructions from DNA to the ribosomes, where it is read in three-base codons.
- TranscriptionTranscription is the process in which a cell copies the DNA sequence of a gene into a matching strand of RNA.
- Gene expressionGene expression is the use of a gene's information to make a working product, usually a protein or a functional RNA molecule.
- ProteinA protein is a large molecule made of one or more chains of amino acids, folded into a specific shape that determines its job in the body.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Biology 2e, 15.4 RNA Processing in Eukaryotes
- NHGRI Talking Glossary: Alternative Splicing
- NCBI MeSH: RNA Splicing
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