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XB-ART-25219
J Cell Biol 1991 Jan 01;1122:215-23.
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Multiple pathways in nuclear transport: the import of U2 snRNP occurs by a novel kinetic pathway.

Michaud N , Goldfarb DS .


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Protein import to the nucleus is a signal-mediated process that exhibits saturation kinetics. We investigated whether signal bearing proteins compete with U2 and U6 snRNPs during import. When injected into Xenopus oocytes, saturating concentrations of P(Lys)-BSA, a protein bearing multiple nuclear localization signals from SV40 large T-antigen, reduce the rate of [125I]P(Lys)-BSA and of [125I]nucleoplasmin import, consistent with their competing for and sharing the same limiting component of the import apparatus. In contrast, saturating concentrations of P(Lys)-BSA do not reduce the rate of HeLa [32P]U2 snRNP assembly or import. The import of U6 snRNP is also competed by P(Lys)-BSA. We conclude that U2 snRNP is imported into oocyte nuclei by a kinetic pathway that is distinct from the one followed by P(Lys)-BSA, nucleoplasmin, and U6 snRNP.

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Species referenced: Xenopus laevis
Genes referenced: npm1

References [+] :
Adam, Nuclear protein import in permeabilized mammalian cells requires soluble cytoplasmic factors. 1990, Pubmed, Xenbase