What are the most frequent non-canonical sequence motifs at the donor and acceptor splice sites in vertebrates?
["About 1-2% of introns are non-canonical, with the most abundant subtype of non-canonical introns being characterized by GC and AG dinucleotides at their 5'- and 3'-termini, respectively.", 'Our results indicate that the incorporation of non-canonical splice site models yields dramatic improvements in annotating genes containing GC-AG and AT-AC non-canonical introns', 'If we assume that approximately the same situation is true for the whole set of annotated mammalian non-canonical splice sites, then the 99.24% of splice site pairs should be GT-AG, 0.69% GC-AG, 0.05% AT-AC and finally only 0.02% could consist of other types of non-canonical splice sites.']
['There are two major exceptions to the canonical GT-AG dinucleotides at donor and acceptor sites: the GG-AG splice site pairs, recognized through the typical U2 splicing machinery, and the AT-AC splice pairs recognized by the U12 splicing machinery.']
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