RNA splicing, via transesterification reactions spliceosomal catalysis GO:0000375 pre-mRNA splicing factor activity Note that nuclear mRNA, Group I, Group II, and Group III introns are all spliced by a series of two transesterification reactions that occur within the RNA itself, or between two RNAs in trans splicing. Some of these require one or more proteins to stabilize the catalytic conformation, while others are autocatalytic. Note that tRNA introns are spliced by a different catalytic mechanism. Splicing of RNA via a series of two transesterification reactions. GO:0000385 RNA splicing factor activity, transesterification mechanism biological_process GO:0031202 RNA splicing