In higher eukaryotes, genes are interrupted by intervening sequences (introns). After the DNA of a gene is copied into pre-mRNA, these intronic sequences have to be removed and the remaining sequences (exons) are joined.
This process is known as pre-mRNA splicing. Often, a cell can alternatively include or exclude a sequence from the mature mRNA, a process that is known as alternative splicing.
What is alternative splicing??
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Alternative splicing is an important mechanism to create protein diversity. It allows to create more than one protein from a given pre-mRNA, or to switch off the protein by including a stop codon in its mRNA. Alternative splicing pathways are not static, but subject to changes e.g. in development, or in response to outside stimuli. Numerous examples of alternative splicing have been observed in the brain, where this mechanism might contribute to neuronal plasticity.