RNA splicing, via transesterification reactions with bulged adenosine as nucleophile mRNA splicing, via spliceosome nuclear mRNA splicing, via spliceosome nuclear mRNA splicing via U2-type spliceosome Note that although the many U12-type introns have the sequence AT-AC at the intron termini, some introns with these terminal sequences are spliced by the U2-type spliceosome. The distinguishing characteristics are sequences near the 5' splice site and the branch point sequences of the intron. Note that although the majority of U2-type introns have the sequence GU-AG at the intron termini, some introns with these terminal sequences are spliced by the U12-type spliceosome. The distinguishing characteristics are sequences near the 5' splice site and the branch point sequences of the intron. GO:0006375 splicing AT-AC intron GO:0006374 biological_process Reactome:R-HSA-72163 The joining together of exons from one or more primary transcripts of messenger RNA (mRNA) and the excision of intron sequences, via a spliceosomal mechanism, so that mRNA consisting only of the joined exons is produced. splicing GT-AG intron GO:0000398 pre-mRNA splicing mRNA splicing nuclear mRNA splicing via U12-type spliceosome Reactome:R-HSA-72165 mRNA processing