Physical identification of branched intron side-products of splicing in Trypanosoma brucei.
Every mRNA in trypanosomes consists of two exons, a common 5' capped mini-exon or spliced leader and a coding-exon. All evidence suggests that the exons are joined by trans-splicing of two individual precursor RNAs, the mini-exon donor RNA or spliced leader precursor RNA (medRNA) and the pre-mRNA. We studied intermediates of the splicing reaction using denaturing two-dimensional PAGE and structurally identified a group of small (approximately 180-300 nt) non-polyadenylated, Y-shaped branched RNAs. The branched Y-shaped RNAs contain the 105 nt medRNA derived intron, joined in a 2'-5' phosphodiester bond to small heterogeneously sized RNAs. These non-polyadenylated branched Y-shaped RNA molecules are analogous to the lariat shaped introns of higher eukaryotes and presumably represent the released intron-like by-products of a trans-splicing reaction which joins the mini-exon and the major coding-exon.
Ralph
D
D
Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032.
Huang
J
J
Van der Ploeg
L H
LH
D000818:Animals; D015152:Blotting, Northern; D004591:Electrophoresis, Polyacrylamide Gel; D005091:Exons; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D009693:Nucleic Acid Hybridization; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D014158:Transcription, Genetic; D014346:Trypanosoma brucei brucei / Q000235:genetics*
D012322:RNA Precursors; D012333:RNA, Messenger