Identification of a 35S U4/U6.U5 tri-small nuclear ribonucleoprotein (tri-snRNP) complex intermediate in spliceosome assembly.

The de novo assembly and post-splicing reassembly of the U4/U6.U5 tri-snRNP remain to be investigated. We report here that ZIP, a protein containing a CCCH-type zinc finger and a G-patch domain, as characterized by us previously, regulates pre-mRNA splicing independent of RNA binding. We found that ZIP physically associates with ...
the U4/U6.U5 tri-small nuclear ribonucleoprotein (tri-snRNP). Remarkably, the ZIP-containing tri-snRNP, which has a sedimentation coefficient of ∼35S, is a tri-snRNP that has not been described previously. We also found that the 35S tri-snRNP contains hPrp24, indicative of a state in which the U4/U6 di-snRNP is integrating with the U5 snRNP. We found that the 35S tri-snRNP is enriched in the Cajal body, indicating that it is an assembly intermediate during 25S tri-snRNP maturation. We showed that the 35S tri-snRNP also contains hPrp43, in which ATPase/RNA helicase activities are stimulated by ZIP. Our study identified, for the first time, a tri-snRNP intermediate, shedding new light on the de novo assembly and recycling of the U4/U6.U5 tri-snRNP.
Mesh Terms:
Alternative Splicing, Antigens, Neoplasm, Coiled Bodies, HeLa Cells, Humans, Immunoprecipitation, MCF-7 Cells, Microscopy, Electron, Transmission, Microscopy, Fluorescence, Molecular Weight, Mutation, Negative Staining, Oligopeptides, Organelle Biogenesis, Protein Multimerization, Protein Stability, RNA Helicases, RNA-Binding Proteins, Recombinant Fusion Proteins, Repressor Proteins, Ribonucleoprotein, U5 Small Nuclear, Spliceosomes, Ubiquitin-Specific Proteases
J. Biol. Chem.
Date: Dec. 03, 2016
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