A minor class of pre-mRNA introns whose excision requires a spliceosome containing U11, U12, U4atac/U6atac, and U5 snRNPs has been identified in plants, insects, and vertebrates. We have characterized single loci that specify the U6atac and U12 snRNAs of Drosophila melanogaster. P element-mediated disruptions of the U6atac and U12 genes cause lethality during the third instar larval and embryonic stages, respectively, and are rescued by U6atac and U12 transgenes. The P element disruption of U6atac results in excision defects of U12-type introns from several transcripts including an alternative U12-dependent spliced isoform of prospero, a homeodomain protein required for CNS development. Thus, we demonstrate the requirement for the U12 spliceosome in the development of a metazoan organism.
Otake, L. R., Scamborova, P., Hashimoto, C., & Steitz, J. A. (2002). The divergent U12-type spliceosome is required for pre-mRNA splicing and is essential for development in Drosophila. Molecular Cell, 9(2), 439–446. https://doi.org/10.1016/S1097-2765(02)00441-0