Advancement through Mitosis requires rae1 Gene Function in Fission Yeast

Whalen, William; Bharathi, Anekella; Danielewicz, Deborah; Dhar, Ravi

doi:10.1002/(sici)1097-0061(19970930)13:12<1167::aid-yea154>3.3.co;2-f

Cited by 18 publications

(28 citation statements)

References 34 publications

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“…What is the significance of the homology between Rae1 and Bub3? It has been suggested that fission yeast rae1 is involved in the import into the nucleus of proteins required for mitosis (34). Human and Xenopus Mad2, while completely dissimilar in sequence to Bub3, are found along the nuclear envelope in interphase cells and at kinetochores only in mitosis (11,12).…”

Section: Discussionmentioning

confidence: 99%

Retention of the Bub3 checkpoint protein on lagging chromosomes

Martínez-Expósito

Kaplan

Copeland

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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Accurate chromosome segregation at mitosis is ensured both by the intrinsic fidelity of the mitotic machinery and by the operation of checkpoints that monitor chromosomemicrotubule attachment. When unattached kinetochores are present, anaphase is delayed and the time available for chromosome-microtubule capture increases. Genes required for this delay first were identified in budding yeast (the MAD and BUB genes), but it is not yet known how the checkpoint senses unattached chromosomes or how it signals cell-cycle arrest. We report the isolation and analysis of a murine homologue of BUB3, a gene whose deletion abolishes mitotic checkpoint function in Saccharomyces cerevisiae. mBub3 belongs to a small gene family that has been highly conserved through evolution. By expressing recombinant proteins in insect cells, we show that mBub3, like yeast Bub3p, binds to Bub1 to form a complex with protein kinase activity. During prophase and prometaphase, preceding kinetochore-microtubule attachment, Bub3 localizes to kinetochores. High levels of mBub3 remain associated with lagging chromosomes but not with correctly aligned chromosomes during metaphase, consistent with a role for Bub3 in sensing microtubule attachment. Intriguingly, the number of lagging chromosomes with high Bub3 staining increases dramatically in cells treated with low (and pharmacologically relevant) concentrations of the chemotherapeutic taxol and the microtubule poison nocodazole.

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Section: Discussionmentioning

confidence: 99%

Retention of the Bub3 checkpoint protein on lagging chromosomes

Martínez-Expósito

Kaplan

Copeland

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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“…Gle2 has recently been proposed to have a mitotic role as a checkpoint protein (50,51). A partial localization to the kinetochore was demonstrated using a FLAG-tagged Gle2 protein (52).…”

Section: Fig 6 Gle2 Bound To Nup98 No Longer Interacts With Tapmentioning

confidence: 99%

Complex Formation among the RNA Export Proteins Nup98, Rae1/Gle2, and TAP

Blevins

Smith

Phillips

et al. 2003

Journal of Biological Chemistry

123

117

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Most nucleocytoplasmic traffic through the nuclear pore complex is mediated by soluble receptors of the importin/exportin or karyopherin family. mRNA export is unique in that no receptor of this family has been implicated in trafficking of the bulk of mRNAs. Instead, many diverse proteins have been linked to mRNA export, but an all-encompassing model remains elusive. Understanding how these proteins interact with each other is central to the development of such a model. Here, we have focused on the interactions between three proteins implicated in mRNA export, Nup98, Rae1/ Gle2, and TAP. We have defined the binary complexes that form among these proteins. We find that Gle2 requires two sites within TAP for stable interaction. Strikingly, rather than a general affinity for all nucleoporin FG repeats, TAP has highest affinity for a specific region within the GLFG domain of Nup98, indicating that not all repeats are identical in function. We have established that the ternary complex can form through simultaneous binding of both Gle2 and TAP to adjacent sites on Nup98. In contrast, Nup98 competes with TAP for Gle2 binding; when bound to Nup98, Gle2 no longer interacts directly with TAP. From these interactions, we propose that Gle2 may act to deliver TAP to Nup98 and that this may represent the first in a series of interactions between an export complex and a nucleoporin.Traffic between the nucleus and cytoplasm proceeds exclusively through the nuclear pore complex, a multiprotein complex of ϳ125 MDa in vertebrate cells (1-3). This immense structure is assembled from surprisingly few constituent proteins or nucleoporins; ϳ30 proteins make up the NPC in both yeast and metazoans (4,5). This seemingly low number may reflect the highly symmetrical nature of the pore. The bulk of the pore structure has 8-fold symmetry around a central axis perpendicular to the plane of the envelope with most nucleoporins present in 8, 16, or 32 copies per pore. The exact mechanism by which the nuclear pore carries out translocation is still uncertain, although several models are under investigation.In addition to the pore complex itself, a number of soluble proteins are essential for nucleocytoplasmic transport. A large family of nuclear transport receptors termed importins/exportins or karyopherins recognize cargoes through specific import or export signal sequences (6 -8). Assembly and disassembly of the receptors and their cargo are highly regulated by the GTPase Ran. Strict compartmentalization of the Ran accessory factors, the cytoplasmic Ran GAP and the nuclear Ran GEF (RCC1), generates a Ran gradient across the nuclear envelope, which regulates the assembly and disassembly of receptorcargo complexes (9). Different members of the importin/ exportin receptor family specialize in the trafficking of specific cargoes. Import of the classical, basic nuclear localization sequence is mediated by the importin ␣/␤ heterodimer, and other protein classes, such as ribosomal proteins, have dedicated import receptors. The workhorse of nuclear pr...

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“…In other cut21 and cut22 mutant cells, 20S cyclosome appeared to be made, although the level in cut22 mutant might be low. The cut21 gene was isolated, and nucleotide sequence determination indicated that cut21 was identical to rae1 required for RNA export (Brown et al 1995;Whalen et al 1997). cut21-497 mutant cells were arrested at metaphase and the frequency of cut phenotypes was very low.…”

Section: Discussionmentioning

confidence: 99%