The HeLa 200 kDa U5 snRNP-specific protein and its homologue in Saccharomyces cerevisiae are members of the DEXH-box protein family of putative RNA helicases

EMBO J. 1996 Aug 1;15(15):4001-15.


The primary structure of the 200 kDa protein of purified HeLa U5 snRNPs (U5-200kD) was characterized by cloning and sequencing of its cDNA. In order to confirm that U5-200kD is distinct from U5-220kD we demonstrate by protein sequencing that the human U5-specific 220 kDa protein is homologous to the yeast U5-specific protein Prp8p. A 246 kDa protein (Snu246p) homologous to U5-200kD was identified in Saccharomyces cerevisiae. Both proteins contain two conserved domains characteristic of the DEXH-box protein family of putative RNA helicases and RNA-stimulated ATPases. Antibodies raised against fusion proteins produced from fragments of the cloned mammalian cDNA interact specifically with the HeLa U5-200kD protein on Western blots and co-immunoprecipitate U5 snRNA and to a lesser extent U4 and U6 snRNAs from HeLa snRNPs. Similarly, U4, U5 and U6 snRNAs can be co-immunoprecipitated from yeast splicing extracts containing an HA-tagged derivative of Snu246p with HA-tag specific antibodies. U5-200kD and Snu246p are thus the first putative RNA helicases shown to be intrinsic components of snRNPs. Disruption of the SNU246 gene in yeast is lethal and leads to a splicing defect in vivo, indicating that the protein is essential for splicing. Anti-U5-200kD antibodies specifically block the second step of mammalian splicing in vitro, demonstrating for the first time that a DEXH-box protein is involved in mammalian splicing. We propose that U5-200kD and Snu246p promote one or more conformational changes in the dynamic network of RNA-RNA interactions in the spliceosome.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antibodies
  • Base Sequence
  • Genes, Fungal
  • Genes, Homeobox
  • HeLa Cells
  • Homeodomain Proteins / chemistry
  • Humans
  • Molecular Sequence Data
  • Molecular Weight
  • Plasmids / metabolism
  • RNA Helicases
  • RNA Nucleotidyltransferases / chemistry*
  • RNA Nucleotidyltransferases / metabolism
  • RNA Precursors / metabolism
  • RNA Splicing
  • Ribonucleoprotein, U5 Small Nuclear / chemistry*
  • Ribonucleoprotein, U5 Small Nuclear / metabolism
  • Saccharomyces cerevisiae
  • Sequence Homology, Amino Acid


  • Antibodies
  • Homeodomain Proteins
  • RNA Precursors
  • Ribonucleoprotein, U5 Small Nuclear
  • RNA Nucleotidyltransferases
  • RNA Helicases