Mammalian U6 small nuclear RNA undergoes 3' end modifications within the spliceosome.
Mammalian U6 small nuclear RNA (snRNA) is heterogeneous with respect to the number of 3' terminal U residues. The major form terminates with five U residues and a 2',3' cyclic phosphate. Because of the presence in HeLa cell nuclear extracts of a terminal uridylyl transferase, a minor form of U6 snRNA is elongated, producing multiple species containing up to 12 U residues. In this study we have used glycerol gradients to demonstrate that these U6 snRNA forms are assembled into U6 ribonucleoprotein (RNP), U4/U6 snRNPs, and U4/U5/U6 tri-snRNP complexes. Furthermore, glycerol gradients combined with affinity selection of biotinylated pre-mRNAs led us to show that elongated forms of U6 snRNAs enter the spliceosome and that some of these become shortened with time to a single species having the same characteristics as the major form of U6 snRNA present in mammalian nuclear extracts. We propose that this elongation-shortening process is related to the function of U6 snRNA in mammalian pre-mRNA splicing.
Tazi
J
J
Laboratoire de Biochimie, CRLC Val d'Aurelle-Paul Lamarque, Parc Euromédecine, Montpellier, France.
Forne
T
T
Jeanteur
P
P
Cathala
G
G
Brunel
C
C
D001482:Base Composition; D002467:Cell Nucleus / Q000378:metabolism; D002474:Cell-Free System; D014644:Genetic Variation; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D009690:Nucleic Acid Conformation; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000302:isolation & purification / Q000378:metabolism*; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism*; D014158:Transcription, Genetic; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase / Q000378:metabolism; D014542:Uridine Monophosphate / Q000378:metabolism*
D046911:Macromolecular Substances; D012322:RNA Precursors; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D014542:Uridine Monophosphate; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase