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J Cell Biol 2010 Aug 23;1904:603-12. doi: 10.1083/jcb.201004109.
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Cajal body surveillance of U snRNA export complex assembly.

Suzuki T , Izumi H , Ohno M .

Phosphorylated adaptor for RNA export (PHAX) is the key export mediator for spliceosomal U small nuclear RNA (snRNA) precursors in metazoa. PHAX is enriched in Cajal bodies (CBs), nuclear subdomains involved in the biogenesis of small ribonucleoproteins. However, CBs' role in U snRNA export has not been demonstrated. In this study, we show that U snRNA precursors microinjected into Xenopus laevis oocyte nuclei temporarily concentrate in CBs but gradually decrease as RNA export proceeds. Inhibition of PHAX activity by the coinjection of a specific anti-PHAX antibody or a dominant-negative PHAX mutant inhibits U snRNA export and simultaneously enhances accumulation of U snRNA precursors in CBs, indicating that U snRNAs transit through CBs before export and that binding to PHAX is required for efficient exit of U snRNAs from CBs. Similar results were obtained with U snRNAs transcribed from microinjected genes. These results reveal a novel function for CBs, which ensure that U snRNA precursors are properly bound by PHAX.

PubMed ID: 20733056
PMC ID: PMC2928011
Article link: J Cell Biol

Species referenced: Xenopus laevis
Genes referenced: coil mt-tr phax trna xpo1
Antibodies: Coil Ab3 Uts2b Ab1

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References [+] :
Abbott, The stem-loop binding protein (SLBP1) is present in coiled bodies of the Xenopus germinal vesicle. 1999, Pubmed, Xenbase