Formation of 2',3'-cyclic phosphates at the 3' end of human U6 small nuclear RNA in vitro. Identification of 2',3'-cyclic phosphates at the 3' ends of human signal recognition particle and mitochondrial RNA processing RNAs.
Approximately 90% of human U6 small nuclear RNA (snRNA) contains uridine cyclic phosphate (U>p) at its 3'-end (Lund, E., and Dahlberg, J. E. (1992) Science 255, 327-330). We studied the formation of U>p at the 3' end of human U6 snRNA using an in vitro system where uridylic acid residues are added from UTP precursor and U>p is formed. Analysis of U6 snRNAs with varying number of uridylic acid residues showed that each of these species contains U>p where the phosphate originated from alpha-phosphate of UTP precursor. The cyclic phosphate formation occurred on U6 snRNA in extracts where essential spliceosomal snRNAs were specifically degraded, thereby indicating that U>p formation is not coupled to pre-mRNA splicing. A subpopulation of human signal recognition particle and mitochondrial RNA processing RNAs isolated from HeLa cells also contained cyclic phosphates at their 3' ends. These data suggest that U>p in U6 snRNA is unlikely to be related to its participation in splicing of pre-mRNAs. It appears that cyclic phosphate is an intermediate product in the metabolism of these small RNAs.
Gu
J
J
Baylor College of Medicine, Department of Pharmacology, Houston, Texas 77030, USA.
Shumyatsky
G
G
Makan
N
N
Reddy
R
R
D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D010755:Organophosphates / Q000378:metabolism*; D010449:Peptide Mapping; D012313:RNA / Q000378:metabolism*; D012326:RNA Splicing; D000077278:RNA, Mitochondrial; D012342:RNA, Small Nuclear / Q000378:metabolism*; D018271:Signal Recognition Particle / Q000378:metabolism*; D014542:Uridine Monophosphate / Q000378:metabolism
D010755:Organophosphates; D000077278:RNA, Mitochondrial; D012342:RNA, Small Nuclear; D018271:Signal Recognition Particle; D012313:RNA; D014542:Uridine Monophosphate