Skip to main content
NCBI home page
RNA logoLink to RNA
. 2001 Mar;7(3):351–360. doi: 10.1017/s1355838201002278

The evolutionarily conserved region of the U snRNA export mediator PHAX is a novel RNA-binding domain that is essential for U snRNA export.

A Segref 1, I W Mattaj 1, M Ohno 1
PMCID: PMC1370092  PMID: 11333016

Abstract

In metazoa, a subset of spliceosomal U snRNAs are exported from the nucleus after transcription. This export occurs in a large complex containing a U snRNA, the nuclear cap binding complex (CBC), the leucine-rich nuclear export signal receptor CRM1/Xpo1, RanGTP, and the recently identified phosphoprotein PHAX (phosphorylated adaptor for RNA export). Previous results indicated that PHAX made direct contact with RNA, CBC, and Xpo1 in the U snRNA export complex. We have now performed a systematic characterization of the functional domains of PHAX. The most evolutionarily conserved region of PHAX is shown to be a novel RNA-binding domain that is essential for U snRNA export. In addition, PHAX contains two major nuclear localization signals (NLSs) that are required for its recycling to the nucleus after export. The interaction domain of PHAX with CBC is at least partly distinct from the RNA-binding domain and the NLSs. Thus, the different interaction domains of PHAX allow it to act as a scaffold for the assembly of U snRNA export complexes.

Full Text

The Full Text of this article is available as a PDF (859.4 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Altschul S. F., Madden T. L., Schäffer A. A., Zhang J., Zhang Z., Miller W., Lipman D. J. Gapped BLAST and PSI-BLAST: a new generation of protein database search programs. Nucleic Acids Res. 1997 Sep 1;25(17):3389–3402. doi: 10.1093/nar/25.17.3389. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Cole C. N., Hammell C. M. Nucleocytoplasmic transport: driving and directing transport. Curr Biol. 1998 May 21;8(11):R368–R372. doi: 10.1016/s0960-9822(98)70239-8. [DOI] [PubMed] [Google Scholar]
  3. Dahlberg J. E., Lund E. Functions of the GTPase Ran in RNA export from the nucleus. Curr Opin Cell Biol. 1998 Jun;10(3):400–408. doi: 10.1016/s0955-0674(98)80017-3. [DOI] [PubMed] [Google Scholar]
  4. Denti M. A., Martínez de Alba A. E., Sägesser R., Tsagris M., Tabler M. A novel RNA-binding protein from Triturus carnifex identified by RNA-ligand screening with the newt hammerhead ribozyme. Nucleic Acids Res. 2000 Mar 1;28(5):1045–1052. doi: 10.1093/nar/28.5.1045. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Dingwall C., Laskey R. A. Nuclear targeting sequences--a consensus? Trends Biochem Sci. 1991 Dec;16(12):478–481. doi: 10.1016/0968-0004(91)90184-w. [DOI] [PubMed] [Google Scholar]
  6. Fischer U., Huber J., Boelens W. C., Mattaj I. W., Lührmann R. The HIV-1 Rev activation domain is a nuclear export signal that accesses an export pathway used by specific cellular RNAs. Cell. 1995 Aug 11;82(3):475–483. doi: 10.1016/0092-8674(95)90436-0. [DOI] [PubMed] [Google Scholar]
  7. Flaherty S. M., Fortes P., Izaurralde E., Mattaj I. W., Gilmartin G. M. Participation of the nuclear cap binding complex in pre-mRNA 3' processing. Proc Natl Acad Sci U S A. 1997 Oct 28;94(22):11893–11898. doi: 10.1073/pnas.94.22.11893. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Fornerod M., Ohno M., Yoshida M., Mattaj I. W. CRM1 is an export receptor for leucine-rich nuclear export signals. Cell. 1997 Sep 19;90(6):1051–1060. doi: 10.1016/s0092-8674(00)80371-2. [DOI] [PubMed] [Google Scholar]
  9. Goldfarb D. S., Gariépy J., Schoolnik G., Kornberg R. D. Synthetic peptides as nuclear localization signals. Nature. 1986 Aug 14;322(6080):641–644. doi: 10.1038/322641a0. [DOI] [PubMed] [Google Scholar]
  10. Grüter P., Tabernero C., von Kobbe C., Schmitt C., Saavedra C., Bachi A., Wilm M., Felber B. K., Izaurralde E. TAP, the human homolog of Mex67p, mediates CTE-dependent RNA export from the nucleus. Mol Cell. 1998 Apr;1(5):649–659. doi: 10.1016/s1097-2765(00)80065-9. [DOI] [PubMed] [Google Scholar]
  11. Görlich D., Henklein P., Laskey R. A., Hartmann E. A 41 amino acid motif in importin-alpha confers binding to importin-beta and hence transit into the nucleus. EMBO J. 1996 Apr 15;15(8):1810–1817. [PMC free article] [PubMed] [Google Scholar]
  12. Görlich D., Kraft R., Kostka S., Vogel F., Hartmann E., Laskey R. A., Mattaj I. W., Izaurralde E. Importin provides a link between nuclear protein import and U snRNA export. Cell. 1996 Oct 4;87(1):21–32. doi: 10.1016/s0092-8674(00)81319-7. [DOI] [PubMed] [Google Scholar]
  13. Görlich D., Kutay U. Transport between the cell nucleus and the cytoplasm. Annu Rev Cell Dev Biol. 1999;15:607–660. doi: 10.1146/annurev.cellbio.15.1.607. [DOI] [PubMed] [Google Scholar]
  14. Hamm J., Mattaj I. W. Monomethylated cap structures facilitate RNA export from the nucleus. Cell. 1990 Oct 5;63(1):109–118. doi: 10.1016/0092-8674(90)90292-m. [DOI] [PubMed] [Google Scholar]
  15. Hood J. K., Silver P. A. In or out? Regulating nuclear transport. Curr Opin Cell Biol. 1999 Apr;11(2):241–247. doi: 10.1016/s0955-0674(99)80032-5. [DOI] [PubMed] [Google Scholar]
  16. Izaurralde E., Adam S. Transport of macromolecules between the nucleus and the cytoplasm. RNA. 1998 Apr;4(4):351–364. [PMC free article] [PubMed] [Google Scholar]
  17. Izaurralde E., Lewis J., Gamberi C., Jarmolowski A., McGuigan C., Mattaj I. W. A cap-binding protein complex mediating U snRNA export. Nature. 1995 Aug 24;376(6542):709–712. doi: 10.1038/376709a0. [DOI] [PubMed] [Google Scholar]
  18. Izaurralde E., Lewis J., McGuigan C., Jankowska M., Darzynkiewicz E., Mattaj I. W. A nuclear cap binding protein complex involved in pre-mRNA splicing. Cell. 1994 Aug 26;78(4):657–668. doi: 10.1016/0092-8674(94)90530-4. [DOI] [PubMed] [Google Scholar]
  19. Izaurralde E., McGuigan C., Mattaj I. W. Nuclear localization of a cap-binding protein complex. Cold Spring Harb Symp Quant Biol. 1995;60:669–675. doi: 10.1101/sqb.1995.060.01.072. [DOI] [PubMed] [Google Scholar]
  20. Jarmolowski A., Boelens W. C., Izaurralde E., Mattaj I. W. Nuclear export of different classes of RNA is mediated by specific factors. J Cell Biol. 1994 Mar;124(5):627–635. doi: 10.1083/jcb.124.5.627. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Kataoka N., Ohno M., Moda I., Shimura Y. Identification of the factors that interact with NCBP, an 80 kDa nuclear cap binding protein. Nucleic Acids Res. 1995 Sep 25;23(18):3638–3641. doi: 10.1093/nar/23.18.3638. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Lührmann R., Kastner B., Bach M. Structure of spliceosomal snRNPs and their role in pre-mRNA splicing. Biochim Biophys Acta. 1990 Nov 30;1087(3):265–292. doi: 10.1016/0167-4781(90)90001-i. [DOI] [PubMed] [Google Scholar]
  23. Maizel J. V., Jr, Lenk R. P. Enhanced graphic matrix analysis of nucleic acid and protein sequences. Proc Natl Acad Sci U S A. 1981 Dec;78(12):7665–7669. doi: 10.1073/pnas.78.12.7665. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Mattaj I. W., Englmeier L. Nucleocytoplasmic transport: the soluble phase. Annu Rev Biochem. 1998;67:265–306. doi: 10.1146/annurev.biochem.67.1.265. [DOI] [PubMed] [Google Scholar]
  25. Ohno M., Fornerod M., Mattaj I. W. Nucleocytoplasmic transport: the last 200 nanometers. Cell. 1998 Feb 6;92(3):327–336. doi: 10.1016/s0092-8674(00)80926-5. [DOI] [PubMed] [Google Scholar]
  26. Ohno M., Segref A., Bachi A., Wilm M., Mattaj I. W. PHAX, a mediator of U snRNA nuclear export whose activity is regulated by phosphorylation. Cell. 2000 Apr 14;101(2):187–198. doi: 10.1016/S0092-8674(00)80829-6. [DOI] [PubMed] [Google Scholar]
  27. Palacios I., Weis K., Klebe C., Mattaj I. W., Dingwall C. RAN/TC4 mutants identify a common requirement for snRNP and protein import into the nucleus. J Cell Biol. 1996 May;133(3):485–494. doi: 10.1083/jcb.133.3.485. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Thompson J. D., Gibson T. J., Plewniak F., Jeanmougin F., Higgins D. G. The CLUSTAL_X windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res. 1997 Dec 15;25(24):4876–4882. doi: 10.1093/nar/25.24.4876. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Truant R., Cullen B. R. The arginine-rich domains present in human immunodeficiency virus type 1 Tat and Rev function as direct importin beta-dependent nuclear localization signals. Mol Cell Biol. 1999 Feb;19(2):1210–1217. doi: 10.1128/mcb.19.2.1210. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Visa N., Izaurralde E., Ferreira J., Daneholt B., Mattaj I. W. A nuclear cap-binding complex binds Balbiani ring pre-mRNA cotranscriptionally and accompanies the ribonucleoprotein particle during nuclear export. J Cell Biol. 1996 Apr;133(1):5–14. doi: 10.1083/jcb.133.1.5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Weis K., Ryder U., Lamond A. I. The conserved amino-terminal domain of hSRP1 alpha is essential for nuclear protein import. EMBO J. 1996 Apr 15;15(8):1818–1825. [PMC free article] [PubMed] [Google Scholar]

Articles from RNA are provided here courtesy of The RNA Society

RESOURCES