The Human U5-220kD Protein (hPrp8) Forms a Stable RNA-Free Complex with Several U5-Specific Proteins, Including an RNA Unwindase, a Homologue of Ribosomal Elongation Factor EF-2, and a Novel WD-40 Protein
- 1 November 1998
- journal article
- research article
- Published by Informa UK Limited in Molecular and Cellular Biology
- Vol. 18 (11), 6756-6766
- https://doi.org/10.1128/mcb.18.11.6756
Abstract
The human small nuclear ribonucleoprotein (snRNP) U5 is biochemically the most complex of the snRNP particles, containing not only the Sm core proteins but also 10 particle-specific proteins. Several of these proteins have sequence motifs which suggest that they participate in conformational changes of RNA and protein. Together, the specific proteins comprise 85% of the mass of the U5 snRNP particle. Therefore, protein-protein interactions should be highly important for both the architecture and the function of this particle. We investigated protein-protein interactions using both native and recombinant U5-specific proteins. Native U5 proteins were obtained by dissociation of U5 snRNP particles with the chaotropic salt sodium thiocyanate. A stable, RNA-free complex containing the 116-kDa EF-2 homologue (116kD), the 200kD RNA unwindase, the 220kD protein, which is the orthologue of the yeast Prp8p protein, and the U5-40kD protein was detected by sedimentation analysis of the dissociated proteins. By cDNA cloning, we show that the 40kD protein is a novel WD-40 repeat protein and is thus likely to mediate regulated protein-protein interactions. Additional biochemical analyses demonstrated that the 220kD protein binds simultaneously to the 40- and the 116kD proteins and probably also to the 200kD protein. Since the 220kD protein is also known to contact both the pre-mRNA and the U5 snRNA, it is in a position to relay the functional state of the spliceosome to the other proteins in the complex and thus modulate their activity.Keywords
This publication has 59 references indexed in Scilit:
- TLP1: A Gene Encoding a Protein Component of Mammalian Telomerase Is a Novel Member of WD Repeats FamilyCell, 1997
- An RNA-dependent ATPase associated with U2/U6 snRNAs in pre-mRNA splicingNature, 1996
- The ancient regulatory-protein family of WD-repeat proteinsNature, 1994
- Isolation of S. cerevisiae snRNPs: comparison of U1 and U4/U6.U5 to Their Human CounterpartsScience, 1994
- Genetic evidence for base pairing between U2 and U6 snRNA in mammalian mRNA splicingNature, 1991
- Base pairing between U2 and U6 snRNAs is necessary for splicing of a mammalian pre-mRNANature, 1991
- Nuclear import-export: In search of signals and mechanismsCell, 1991
- A cold-sensitive mRNA splicing mutant is a member of the RNA helicase gene family.Genes & Development, 1991
- Basic Local Alignment Search ToolJournal of Molecular Biology, 1990
- Basic local alignment search toolJournal of Molecular Biology, 1990