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RNA splicing. RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre- mRNA) transcript is transformed into a mature messenger RNA (mRNA). It works by removing all the introns (non-coding regions of RNA) and splicing back together exons (coding regions). For nuclear-encoded genes, splicing occurs in the ...
Simple illustration of an unspliced mRNA precursor, with two introns and three exons (top). After the introns have been removed via splicing, the mature mRNA sequence is ready for translation (bottom). A particularly extreme case is the Drosophila dhc7 gene containing a ≥3.6 megabase (Mb) intron, which takes roughly three days to transcribe.
The term exon refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts. In RNA splicing, introns are removed and exons are covalently joined to one another as part of generating the mature RNA. Just as the entire set of genes for a species constitutes the genome, the entire set of exons constitutes the ...
Alternative splicing produces three protein isoforms. Protein A includes all of the exons, whereas Proteins B and C result from exon skipping. Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to produce different splice variants.
Introns and exons are present in both the underlying DNA sequence and the pre-mRNA molecule, therefore, to produce a mature mRNA molecule encoding a protein, splicing must occur. [6] During splicing, the intervening introns are removed from the pre-mRNA molecule by a multi-protein complex known as a spliceosome (composed of over 150 proteins ...
Pre-mRNA has both introns and exons. As a part of the maturation process, RNA splicing removes the non-coding RNA introns leaving behind the exons, which are then spliced and joined together to form the mature mRNA. [3] [8] Splicing is conducted by the spliceosome. The spliceosome is a large ribonucleoprotein which cleaves the RNA at the ...
Exon shuffling is a molecular mechanism for the formation of new genes. It is a process through which two or more exons from different genes can be brought together ectopically, or the same exon can be duplicated, to create a new exon-intron structure. [1] There are different mechanisms through which exon shuffling occurs: transposon mediated ...
There are multiple alternative splicing modes: exon skipping (most common splicing mode in humans and higher eukaryotes), mutually exclusive exons, alternative donor or acceptor sites, intron retention (most common splicing mode in plants, fungi, and protozoa), alternative transcription start site (promoter), and alternative polyadenylation. [118]