p110, a novel human U6 snRNP protein and U4/U6 snRNP recycling factor.
During each spliceosome cycle, the U6 snRNA undergoes extensive structural rearrangements, alternating between singular, U4-U6 and U6-U2 base-paired forms. In Saccharomyces cerevisiae, Prp24 functions as an snRNP recycling factor, reannealing U4 and U6 snRNAs. By database searching, we have identified a Prp24-related human protein previously described as p110(nrb) or SART3. p110 contains in its C-terminal region two RNA recognition motifs (RRMs). The N-terminal two-thirds of p110, for which there is no counterpart in the S.cerevisiae Prp24, carries seven tetratricopeptide repeat (TPR) domains. p110 homologs sharing the same domain structure also exist in several other eukaryotes. p110 is associated with the mammalian U6 and U4/U6 snRNPs, but not with U4/U5/U6 tri-snRNPs nor with spliceosomes. Recom binant p110 binds in vitro specifically to human U6 snRNA, requiring an internal U6 region. Using an in vitro recycling assay, we demonstrate that p110 functions in the reassembly of the U4/U6 snRNP. In summary, p110 represents the human ortholog of Prp24, and associates only transiently with U6 and U4/U6 snRNPs during the recycling phase of the spliceosome cycle.
Bell
Mathias
M
Institut für Biochemie, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany.
Schreiner
Silke
S
Damianov
Andrey
A
Reddy
Ram
R
Bindereif
Albrecht
A
D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D004252:DNA Mutational Analysis; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000737:chemistry* / Q000502:physiology*; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry* / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D000951:Antigens, Neoplasm; C401305:Prp24 protein, S cerevisiae; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; C431323:SART1 protein, human; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA