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Alternative splicing, alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to produce different splice variants. For example, some exons of a gene may be included within or excluded from the final RNA product of the gene. [ 1 ]
Alternative splicing is regulated so that each mature mRNA may encode a multiplicity of proteins. Alternative splicing of the primary transcript. The effect of alternative splicing in gene expression can be seen in complex eukaryotes which have a fixed number of genes in their genome yet produce much larger numbers of different gene products. [9]
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 ().It works by removing all the introns (non-coding regions of RNA) and splicing back together exons (coding regions).
These include the 5' end splice site, the branch point sequence, the polypyrimidine tract, and the 3' end splice site. The spliceosome catalyzes the removal of introns, and the ligation of the flanking exons. [citation needed] Introns typically have a GU nucleotide sequence at the 5' end splice site, and an AG at the 3' end splice site.
Alternative splicing occurs at both the 5' and 3' ends, and there are several variants (other than the male- and female-specific splicing patterns). [1] The fruitless gene locus also controls the expression of hundreds of other genes, [9] any subset of which may actually regulate behavior.
Where intron-generating transposons do not create target site duplications, elements include both splice sites GT (5') and AG (3') thereby splicing precisely without affecting the protein-coding sequence. [65] It is not yet understood why these elements are spliced, whether by chance, or by some preferential action by the transposon.
The minor spliceosome splices U12-type introns. The two types of introns mainly differ in their splicing sites: U2-type introns have GT-AG 5′ and 3′ splice sites while U12-type introns have AT-AC at their 5′ and 3′ ends. The minor spliceosome carries out its function through a different pathway from the major spliceosome. [citation needed]
The pre-mRNA processing at the 3' end of the RNA molecule involves cleavage of its 3' end and then the addition of about 250 adenine residues to form a poly(A) tail.The cleavage and adenylation reactions occur primarily if a polyadenylation signal sequence (5'- AAUAAA-3') is located near the 3' end of the pre-mRNA molecule, which is followed by another sequence, which is usually (5'-CA-3') and ...