Brl1p -- a novel nuclear envelope protein required for nuclear transport.

Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Traffic (Impact Factor: 4.71). 07/2005; 6(6):502-17. DOI: 10.1111/j.1600-0854.2005.00295.x
Source: PubMed

ABSTRACT In this article, we identify a cold-sensitive mutant of Xpo1p designated as xop1-2 (but will be referred to from here on as xpo1-ok) that is synthetically lethal with srm1-1, a Saccharomyces cerevisiae RCC1 homolog. xpo1-ok was a novel mutated allele with a single point mutation, T283P. Suppressors of xpo1-ok were isolated, and one of them was found to encode a novel nuclear envelope integral membrane protein designated as Brl1p (Brr6 like protein no. 1). Brl1p is homologous with Brr6p at the C-terminal domain, which is well conserved in the Brr6/Brl1 family. To characterize the function of Brl1p, a series of temperature-sensitive mutants of Brl1p were isolated. All of brl1 mutations were localized to the conserved C-terminal domain that is essential for a function of Brl1p. Some brl1 alleles showed defects in nuclear export of either mRNA or protein, and nuclear pore clustering, similar to brr6-1. The cellular localization of Brl1p is also similar to that of Brr6p. The genetic analysis suggested that Brl1p functionally interacts with Brr6p. An interaction of Brl1p with Brr6p was shown by the two-hybrid method. We hypothesize that Brl1p functions for nuclear export as a complex with Brr6p.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The defining feature of eukaryotic cells is the double lipid bilayer of the nuclear envelope (NE) that serves as a physical barrier separating the genome from the cytosol. Nuclear pore complexes (NPCs) are embedded in the NE to facilitate transport of proteins and other macromolecules into and out of the nucleus. In fungi and early embryos where the NE does not completely breakdown during mitosis, microtubule-organizing centers such as the spindle pole body (SPB) must also be inserted into the NE to facilitate organization of the mitotic spindle. Several recent papers have shed light on the mechanism by which SPB complexes are inserted into the NE. An unexpected link between the SPB and NPCs suggests that assembly of these NE complexes is tightly coordinated. We review the findings of these reports in light of our current knowledge of SPB, NPC and NE structure, assembly and function.
    Nucleus (Austin, Texas) 05/2012; 3(3):226-36. DOI:10.4161/nucl.20148 · 3.15 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A defining feature of eukaryotic cells is the nucleus, which houses the genome inside the nuclear envelope (NE): a double lipid bilayer that separates the nuclear and cytoplasmic materials. Although the NE is commonly viewed as a barrier that is overcome only by embedded nuclear pore complexes (NPCs) that facilitate nuclear-cytoplasmic trafficking, recent work in a wide range of eukaryotes reveals that the NE is a dynamic organelle that is modified each time the cell divides to ultimately establish two functional daughter nuclei. Here, we review how studies of divergent mitotic strategies have helped elucidate common properties of NE biology that allow it to function throughout the cell cycle.
    Current opinion in cell biology 02/2014; 26C:1-9. DOI:10.1016/ · 8.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The fission yeast interphase spindle pole body (SPB) is a bipartite structure in which a bulky cytoplasmic domain is separated from a nuclear component by the nuclear envelope. During mitosis, the SPB is incorporated into a fenestra that forms within the envelope during mitotic commitment. Closure of this fenestra during anaphase B/mitotic exit returns the cytoplasmic component to the cytoplasmic face of an intact interphase nuclear envelope. Here we show that Brr6 is transiently recruited to SPBs at both SPB insertion and extrusion. Brr6 is required for both SPB insertion and nuclear envelope integrity during anaphase B/mitotic exit. Genetic interactions with apq12 and defective sterol assimilation suggest that Brr6 may alter envelope composition at SPBs to promote SPB insertion and extrusion. The restriction of the Brr6 domain to eukaryotes that use a polar fenestra in an otherwise closed mitosis suggests a conserved role in fenestration to enable a single microtubule organizing center to nucleate both cytoplasmic and nuclear microtubules on opposing sides of the nuclear envelope.
    The Journal of Cell Biology 10/2011; 195(3):467-84. DOI:10.1083/jcb.201106076 · 9.69 Impact Factor

Full-text (2 Sources)

Available from
Oct 14, 2014