Practice question

Most eukaryotic introns follow GT-AG rule with GU at five prime end and AG at three prime end recognized by major U2-dependent spliceosome comprising U1, U2, U4, U5, U6 small nuclear RNPs. Rare introns with AU at five prime and AC at three prime, as well as subset of GU-AG introns with distinct branch site consensus, are removed by minor or U12-dependent spliceosome comprising U11, U12, U4atac, U6atac, U5 snRNPs. U11-U12 di-snRNP functionally analogous to U1-U2. Minor introns occur in genes encoding ion channels, DNA repair proteins, and are highly conserved evolutionarily.