Trans splicing of mRNA precursors.

Using modified adenovirus and beta-globin transcription units, I constructed pairs of transcripts that contained mutually complementary sequences in their introns. Upon incubation of the annealed transcripts in a cell-free splicing system, an exon from one member of the dimeric complex was accurately spliced to an exon from the other. The occurrence of such intermolecular, or trans, splicing in vitro raises the possibility that some of the mRNAs in a cell acquire exons from more than one primary transcript.