• Korean Journal of Microbiology
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• v.32 no.1
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• pp.12-19
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• 1994

KEM1 is known to control the spindle pole body or microtubule function, probably in response to the cellular nutritional conditions in Saccharomyces cerevisiae. Transposon insertions were performed in the cloned KEM1 gene using mini-Tn10-LUK element carrying E. coli ${\beta}$-galactosidase structural gene. A collection of ranfom Tn10-LUK insertions defined an approximately 3.5 kb region required for the KEM1 function. From this collection functional KEM1::lacZ protein fusions were identified. Indirect immunofluorescence using anti-${\beta}$-galacatosidase antibodies localized the KEM1::lacZ fusion protein to the periphery of the nucleus.

• BMB Reports
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• v.32 no.1
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• pp.92-97
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• 1999

Cytokinesis and septation should be coordinated to nuclear division in the cell division cycle for precise transmission of the genome into daughter cells. byr4, an essential gene in fission yeast Schizosaccharomyces pombe, regulates the timing of cytokinesis and septation in a dosage-dependent manner. We examined the intracellular localization of the Byr4 protein by expressing byr4 as a fusion of green fluorescence protein (GFP). The Byr4 protein localizes as a single dot on the nuclear periphery of interphase cells, duplicates before mitosis, and the duplicated dots segregate with the nuclei in anaphase. The behavior of Byr4p throughout the cell cycle strongly suggests that Byr4p is localized to the spindle pole body (SPB), a microtubule organizing center (MTOC) in yeast. The presence of the Byr4 protein in the SPB is consistent with its function to coordinate mitosis and cytokinesis. We also mapped the domains of Byr4p for its proper localization to SPB by expressing various byr4 deletion mutants as GFP fusions. Analyses of the diverse byr4 deletion mutants suggest that the indirect repeats and the regions homologous to the open reading frame (ORF) YJR053W of S. cerevisiae in its C-terminus are essential for its localization to the SPB.

• The Korean Journal of Mycology
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• v.24 no.1 s.76
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• pp.1-7
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• 1996

Premitotic, mitotic and postmitotic nuclei in the dikaryotic somatic hyphae of Pleurotus ostreatus, the oyster mushroom fungus were ultrastucturally examined using chemical fixation and freeze-substitution process, and the behaviors of astral microtubules associated with these nuclei were closely analyzed. Electron microscopic examinations revealed that astral microtubules are significantly abundant when the nuclei are in the stage of migration and at the stage of migration, the separation of spindle pole body occurs. Such an abundancy of astral microtubules in premitotic migrating nuclei is well contrasted with mitotic and postmitotic nuclei with much fewer astral microtubules and it should be noted that neither of these latter classes of nuclei exhibits the separation of the spindle pole body. It is remarkable that the postmitotic nuclei that are believed to migrate actively are associated with the astral microtubules that are less in numbers and length. During all the stages of nuclear division, astral microtubules are invariably radiating from the spindle pole bodies and nucleolus remains within the nuclear envelope of dividing nuclei throughout the division. The functions of astral microtubules developed during the nuclear division as well as the nuclear migration and separation of the spindle pole body were closely examined.

• Proceedings of the Zoological Society Korea Conference
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• 1994.10a
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• pp.246.2-246
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• 1994

• Journal of Plant Biology
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• v.30 no.4
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• pp.225-247
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• 1987

Meiosis and postmeiotic mitosis in Boletus rubinellus were examined ultrastructurally. Meriosis occurred at the apex of the basidium. A sausage-shaped spindle pole body(SPB) was observed along with the presence of synaptonemal complexes during pachytene and a diglobular SPB was present on late pachytene or diplotene nuclei. During metaphase I, the monoglobular SPB at the spindle pole was surrounded bya membrane and the nuclear enveloope was discontinuous. At anaphase I, the chromosomes became better defined and formed a central spindle. The nucleolus was extruded from the nucleus. During anaphase I, the SPB was excluded from the chromosomal region by a membrane and both poles were fully separated to opposite sides of the basidial wall. In meiosis II, the two nuclei divided synchronously and the spindles were parallel. The spindles were smaller than in meiosis I, while the SPB was approximately the same size as that of the similar stage in meiosis I. During anaphasetelophase II, the SPB was surrounded by a cap of endoplasmic reticulum (ER) that delimited it from the spindle. The postmeiotic interphase nuclei migrated to the mid-region of the basidium before migration to the spores. The SPB at this stage was diglobular. A postmeiotic mitosis occurred within the basidiospore, and the plane of the spindle was obique to the long axis of the spore. The spindle and SPB were smaller than at meiosis I and there were fewer nonchromosomal microtubules. At anaphase, the nucleolus was present inside the nuclear envelope but lateral to the spindle.

• Korean Journal of Microbiology
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• v.30 no.1
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• pp.37-41
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• 1992

The KEM1 gene is known to affect microtubule and spindle pole body function during the cell division cycle in Saccharomjyces cerevisiae. To identify new genes with functions similar or related to those of KEM1, we isolated a high copy suppressor gene (ROK1) that suppresses the kem1 mutation when cloned on a high copy number plasmid but not on a low copy number plasmid. Two clones which suppress both the benomyl hypersensitivity and the $Kar^{-}$ enhancing phenotype of kem1 null mutation were isolated and were shown to have a 9.0 kb identical insert by restriction endonuclease analysis. The restriction map constructed indicates that this suppressor gene, ROK1 is not KEM1. Subcloning experiments suggest that the functional region of ROK1 is at least 3.0kb in size.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.383-387
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• 2016

In fission yeast, Schizosaccharomyces pombe, the cdc31 gene encodes a member of the conserved $Ca^{2+}$-binding centrin/CDC31 family, which is a component of spindle pole body. Here, we demonstrate that the S. pombe cdc31p is also a component of TREX-2 complex, which influences mRNA export from the nucleus to the cytoplasm. Repression of the cdc31 gene expression caused growth defect with accumulation of $poly(A)^+$ RNA in the nucleus. On the other hand, over-expression of cdc31 exhibited no defects of both growth and bulk mRNA export, but showed somewhat longer cell morphology. Yeast two-hybrid analysis showed that Cdc31 interacted with Sac3 and Pci2, the subunits of TREX-2 complex. These results suggest that S. pombe Cdc31 is also involved in mRNA export as a component of TREX-2 complex.

• Journal of Microbiology
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• v.39 no.4
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• pp.286-292
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• 2001

During mitosis. the proper segregation of duplicated chromosomes is corrdinated by a spindle check-point. The bifurcated spindle checkpoint blocks cell cycle progression at metaphase by monitoring unattached kinetochores and inhibits mitotic exit in response to the misorientation of the mitotic spin- dle Ibd1p/Bfa1p is a spindle checkpoint regulator of budding yeast in the Bub2p checkpoint pathway for mitotic exit and its disruption abolishes mitotic arrest when proper organization of the mitotic spin-dls inhibited. Ibd1p/Bfa1p localizes to the spindle pole body, a microtublue-organizing center in yeast, and its overexpression arrests the cell cycle in 80% of cells with an enlarged budy at mitosis and in 20 % of cells with multiple buds. In this study, we found that the C-terminus of Ibd1p/Bfa1p phys-ically interacts with Skp1p, a key component of SCF (Skp1/cullin/F-box) complex for ubiquition-medi-ated proteolysis of cel cycle regulatores as well as an evolutionally conserved kinetochore protein for cell cycle progression. A putative F-box motif was found in the C-terminus of Ibd1p/Bfa1p and its function was investigated by making mutants of conserved residues in the motif. These Ibd1p/Bfa1p mutants of a putative F-box interacted with SKp1p in vitro by two-hybrid assays as wild type Ibd1p/Bfa1p. Also these Ibd1p/Bfa1p utants displayed the overexpression phenotypes of wild type Ibd1p, when over-expressed under inducible promoters . These results suggest that a putative F-box motif of Ibd1p/Bfa1p is not essential for the interaction with SKp1p and its function in mitotic exit and cytokinesis.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.162.2-162.2
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• 2003

Microtubule-organizing center (MOTC) plays pivotal roles in cell division process. Integrity of the spindle pole body (SPB) in Saccharomyces cerevisiae is required for migration and separation of sister chromatids in mitotic phase. Role of an essential SPB component, Spcl05, is poorly understood. Here we show that throughout all stage of cell division cycle, GFP-tagged Spcl05p localizes at SPB and its protein stability is fluctuated with mitosis-specific modifications. To gain new insights into the function of Spc105, we generated and characterized novel temperature sensitive spc105 mutants. (omitted)

• BMB Reports
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• v.45 no.8
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• pp.427-432
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• 2012

Primary cilia, single hair-like appendage on the surface of the most mammalian cells, were once considered to be vestigial cellular organelles for a past century because of their tiny structure and unknown function. Although they lack ancestral motility function of cilia or flagella, they share common ground with multiciliated motile cilia and flagella on internal structure such as microtubule based nine outer doublets nucleated from the base of mother centrioles called basal body. Making cilia, ciliogenesis, in cells depends on the cell cycle stage due to reuse of centrioles for cell division forming mitotic spindle pole (M phase) and assembling cilia from basal body (starting G1 phase and maintaining most of interphase). Ciliary assembly required two conflicting processes such as assembly and disassembly and balance between these two processes determines the length of cilia. Both process required highly conserved transport system to supply needed substance to grow tip of cilia and bring ciliary turnover product back to the base of cilia using motor protein, kinesin and dynein, and transport protein complex, IFT particles. Disruption of ciliary structure or function causes multiple human disorder called ciliopathies affecting disease of diverse ciliated tissues ranging from eye, kidney, respiratory tract and brain. Recent explosion of research on the primary cilia and their involvement on animal development and disease attracts scientific interest on how extensively the function of cilia related to specific cell physiology and signaling pathway. In this review, I introduce general features of primary cilia and recent progress in understanding of the ciliary length control and signaling pathways transduced through primary cilia in vertebrates.