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Alternative donor site: An alternative 5' splice junction (donor site) is used, changing the 3' boundary of the upstream exon. Alternative acceptor site: An alternative 3' splice junction (acceptor site) is used, changing the 5' boundary of the downstream exon. Intron retention: A sequence may be spliced out as an intron or simply retained.
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 ...
Transcription produces primary transcripts that are further modified by several processes. These processes include the 5' cap, 3'-polyadenylation, and alternative splicing. In particular, alternative splicing directly contributes to the diversity of mRNA found in cells.
The spliceosome, [5] a protein-RNA complex located in the nucleus, catalyzes splicing in the following manner: The spliceosome recognizes an intron, which is flanked by specific sequences at its 5' and 3' ends, known as a donor splice site (or 5' splice site) and an acceptor splice site (or 3' splice site), respectively.
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.
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 ...
The suspected mechanism is that alternative 5' splice sites are chosen when SR proteins bind to upstream ESE and interacts with U1-70K and together recruit U1 to the 5' splice site. [8] [17] In constitutive splicing SR proteins bind to U2AF and U1-70K to bridge the gap between the two components of the spliceosome to mark the 3' and 5' splice ...
Five prime untranslated region. The 5′ untranslated region (also known as 5′ UTR, leader sequence, transcript leader, or leader RNA) is the region of a messenger RNA (mRNA) that is directly upstream from the initiation codon. This region is important for the regulation of translation of a transcript by differing mechanisms in viruses ...