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.
Any of a Series of Ribonucleoprotein Complexes That Contain Snrna(s) and Small Nuclear Ribonucleoproteins (snrnps) and Are Formed Sequentially During the Spliceosomal Splicing of One or More Substrate Rnas and Which Also Contain the RNA Substrate(s) From the Initial Target Rnas of Splicing the Splicing Intermediate Rna(s) to the Final RNA Products. During Cis Splicing the Initial Target RNA Is a Single Contiguous RNA Transcript Whether MRNA Snorna Etc. and the Released Products Are a Spliced RNA and an Excised Intron Generally As a Lariat Structure. During Trans Splicing There Are Two Initial Substrate Rnas the Spliced Leader RNA and a Pre Mrna.