Major intron boundary nucleotides are GU-AG. Minor intron boundary nucleotides are AT-AC. Why does the former use RNA Uracil and the latter use DNA thymine? Since introns are in the primary RNA transcript, shouldn't both be RNA and use U rather than T?
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It is not unusual for RNA sequences to be reported with T instead of U; the writer is reporting the cDNA sequence instead of the RNA sequence. In RNA at the boundary of the minor intron, there is a uracil. In the following page, the writers follow the oft-used convention of describing RNA with T instead of U (writing the cDNA sequence). https://en.wikipedia.org/wiki/Minor_spliceosome