Identification and characterization of Uss1p (Sdb23p): a novel U6 snRNA-associated protein with significant similarity to core proteins of small nuclear ribonucleoproteins

EMBO J. 1995 May 1;14(9):2066-75.


The SDB23 gene of Saccharomyces cerevisiae was isolated in a search for high copy-number suppressors of mutations in a cell cycle gene, DBF2, SDB23 encodes a 21,276 Da protein with significant sequence similarity to characterized mammalian snRNP core proteins. Examination of multiple sequence alignments of snRNP core proteins with Sdb23p indicates that all of these proteins share a number of highly conserved residues, and identifies a novel motif for snRNP core proteins. Sdb23p is essential for cell viability and is required for nuclear pre-mRNA splicing both in vivo and in vitro. Extracts prepared from Sdb23p-depleted cells are unable to support splicing and have vastly reduced levels of U6 snRNA. The stability of U1, U2, U4 and U5 spliceosomal snRNAs is not affected by the loss of Sdb23p. Antibodies raised against Sdb23p strongly coimmunoprecipitate free U6 snRNA and U4/U6 base-paired snRNAs. These results establish that SDB23 encodes a novel U6 snRNA-associated protein that is essential for the stability of U6 snRNA. We therefore propose the more logical name USS1 (U-Six SnRNP) for this gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cell Division
  • Chromosome Mapping
  • DNA, Fungal / genetics
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism*
  • Genes, Fungal
  • Humans
  • Molecular Sequence Data
  • RNA Precursors / metabolism
  • RNA Splicing
  • RNA, Fungal / metabolism
  • RNA, Small Nuclear / metabolism*
  • Ribonucleoprotein, U4-U6 Small Nuclear / genetics*
  • Ribonucleoprotein, U4-U6 Small Nuclear / metabolism*
  • Ribonucleoproteins, Small Nuclear / genetics*
  • Ribonucleoproteins, Small Nuclear / metabolism*
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid


  • DNA, Fungal
  • Fungal Proteins
  • LSM4 protein, S cerevisiae
  • RNA Precursors
  • RNA, Fungal
  • RNA, Small Nuclear
  • Ribonucleoprotein, U4-U6 Small Nuclear
  • Ribonucleoproteins, Small Nuclear
  • Saccharomyces cerevisiae Proteins

Associated data

  • GENBANK/X82649