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Natalizio, A.H., Matera, A.G. (2013). Identification and characterization of Drosophila Snurportin reveals a role for the import receptor Moleskin/importin-7 in snRNP biogenesis.  Mol. Biol. Cell 24(18): 2932--2942.
FlyBase ID
FBrf0222706
Publication Type
Research paper
Abstract

Nuclear import is an essential step in small nuclear ribonucleoprotein (snRNP) biogenesis. Snurportin1 (SPN1), the import adaptor, binds to trimethylguanosine (TMG) caps on spliceosomal small nuclear RNAs. Previous studies indicated that vertebrate snRNP import requires importin-β, the transport receptor that binds directly to SPN1. We identify CG42303/snup as the Drosophila orthologue of human snurportin1 (SNUPN). Of interest, the importin-β binding (IBB) domain of SPN1, which is essential for TMG cap-mediated snRNP import in humans, is not well conserved in flies. Consistent with its lack of an IBB domain, we find that Drosophila SNUP (dSNUP) does not interact with Ketel/importin-β. Fruit fly snRNPs also fail to bind Ketel; however, the importin-7 orthologue Moleskin (Msk) physically associates with both dSNUP and spliceosomal snRNPs and localizes to nuclear Cajal bodies. Strikingly, we find that msk-null mutants are depleted of the snRNP assembly factor, survival motor neuron, and the Cajal body marker, coilin. Consistent with a loss of snRNP import function, long-lived msk larvae show an accumulation of TMG cap signal in the cytoplasm. These data indicate that Ketel/importin-β does not play a significant role in Drosophila snRNP import and demonstrate a crucial function for Msk in snRNP biogenesis.

PubMed ID
PubMed Central ID
PMC3771954 (PMC) (EuropePMC)
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    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Mol. Biol. Cell
    Title
    Molecular Biology of the Cell
    Publication Year
    1992-
    ISBN/ISSN
    1059-1524
    Data From Reference
    Aberrations (1)
    Alleles (9)
    Genes (25)
    Physical Interactions (49)
    Cell Lines (1)
    Natural transposons (1)
    Experimental Tools (2)
    Transgenic Constructs (7)