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The contractile ring (CR) consists of bundled actin filaments and myosin II; however, the actin-bundling factor remains elusive. We show that the fission yeast Schizosaccharomyces pombe IQGAP Rng2 is involved in the generation of CR F-actin and required for its arrangement into a ring. An N-terminal fragment of Rng2 is necessary for the function of Rng2 and(More)
Actin-depolymerizing factor (ADF)/cofilin is widely expressed in eukaryotes and plays a central role in reorganizing the actin cytoskeleton by disassembling actin filaments. The ADF-homologous domain (ADF-H) is conserved in several other actin-modulating proteins such as twinfilin, Abp1/drebrin, and coactosin. Although these proteins interact with actin via(More)
The fission yeast Schizosaccharomyces pombe serves as a model system for studying role of actin cytoskeleton, since it has simple actin cytoskeletons and is genetically tractable. In contrast, biochemical approaches using this organism are still developing; fission yeast actin has so far not been isolated in its native form and characterized, and therefore,(More)
Cytokinesis is the final stage of the cell cycle, and ensures completion of both genome segregation and organelle distribution to the daughter cells. Cytokinesis requires the cell to solve a spatial problem (to divide in the correct place, orthogonally to the plane of chromosome segregation) and a temporal problem (to coordinate cytokinesis with mitosis).(More)
During cytokinesis in many eukaryotic cells, myosin-II concentrates at the equatorial cortex with actin filaments (F-actin) and is supposed to generate forces to divide the cell into two, which is called the contractile ring (CR) hypothesis. Several lines of evidence indicate that the myosin-II is recruited independently of F-actin and interacts(More)
The actomyosin-based contractile ring, which assembles at the cell equator, maintains its circularity during cytokinesis in many eukaryotic cells, ensuring its efficient constriction. Although consistent maintenance of the ring is one of the mechanisms underpinning cytokinesis, it has not yet been fully addressed. We here investigated the roles of fission(More)
To obtain a comprehensive picture of microtubule dynamics during conjugation, the mode of sexual reproduction in ciliates, we combined indirect immunofluorescence and three-dimensional imaging using confocal laser-scanning microscope to visualize the cellular localization of DNA, microtubules, and γ-tubulin, the main component of the microtubule-organizing(More)
In the fission yeast Schizosaccharomyces pombe (Sp), Mid1/Dmf1 plays an important role in positioning the division site by inducing formation of the contractile ring (CR). Mid1, emanating from the nucleus located in the cell center, forms a dozen of nodes in the middle cell cortex ahead of mitosis, and actin filaments and myosin II accumulated at each node(More)
Actin-depolymerizing factor (ADF)/cofilin is a well-conserved actin-modulating protein, which induces reorganization of the actin cytoskeleton by severing and depolymerizing F-actin. ADF/cofilin also binds to G-actin and inhibits nucleotide exchange, and hence, is supposed to regulate the nucleotide-bound state of the cellular G-actin pool cooperating with(More)
Iejimalides (IEJLs) A-D are 24-membered macrolides isolated from a tunicate Eudistoma cf. rigida, and exhibit potent cytotoxicity in vitro and antitumor activity in vivo. We previously reported that the molecular target of IEJL-A and -B was the vacuolar-type H(+)-ATPases (V-ATPases). However IEJL-C and -D, which are sulfonylated IEJL-A and -B, respectively,(More)