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Many eukaryotic cell types undergo size-dependent cell cycle transitions controlled by the ubiquitous cyclin-dependent kinase Cdk1 (refs 1-4). The proteins that control Cdk1 activity are well described but their links with mechanisms monitoring cell size remain elusive. In the fission yeast Schizosaccharomyces pombe, cells enter mitosis and divide at a(More)
Among the numerous centrin isoforms identified by two-dimensional gel electrophoresis in human cells, an acidic and slow-migrating isoform is particularly enriched in a centrosome fraction. We report here that this isoform specifically reacts with antibodies raised against Saccharomyces cerevisiae Cdc31p and is present, as other centrin isoforms, in the(More)
Centrin is a member of the calcium-binding EF-hand protein superfamily present in centrosomes of widely divergent species. Investigating the cellular distribution of human centrin by both immunofluorescence and cell fractionation, we report that centrin is biochemically complex in human cells, displaying as much as ten isoforms in 2-D electrophoresis. This(More)
Proper microtubule organization is essential for cellular processes such as organelle positioning during interphase and spindle formation during mitosis. The fission yeast Schizosaccharomyces pombe presents a good model for understanding microtubule organization. We identify fission yeast ase1p, a member of the conserved ASE1/PRC1/MAP65 family of(More)
In eukaryotes, cytokinesis generally involves an actomyosin ring, the contraction of which promotes daughter cell segregation. Assembly of the contractile ring is tightly controlled in space and time. In the fission yeast, contractile ring components are first organized by the anillin-like protein Mid1 into medial cortical nodes. These nodes then coalesce(More)
Septins are filament-forming proteins with a conserved role in cytokinesis. In the fission yeast Schizosaccharomyces pombe, septin rings appear to be involved primarily in cell-cell separation, a late stage in cytokinesis. Here, we identified a protein Mid2p on the basis of its sequence similarity to S. pombe Mid1p, Saccharomyces cerevisiae Bud4p, and(More)
Maintaining genome integrity and cellular function requires proper positioning of the cell division plane. In most eukaryotes, cytokinesis relies on a contractile actomyosin ring positioned by intrinsic spatial signals that are poorly defined at the molecular level. Fission yeast cells assemble a medial contractile ring in response to positive spatial cues(More)
The thermodynamic basis for actin-based motility of Listeria monocytogenes has been investigated using cytoplasmic extracts of Xenopus eggs, initially developed by Theriot et al. (Theriot, J. A., J. Rosenblatt, D. A. Portnoy, P. J. Goldschmidt-Clermont, and T. J. Mitchison. 1994. Cell. 76:505-517) as an in vitro cell-free system. A large proportion (75%) of(More)
The use of green fluorescent protein (GFP) fusions as biosensors for examining protein localization and dynamics has revolutionized cell biology. Here, we describe the methods developed for imaging of GFP-fusions in the fission yeast Schizosaccharomyces pombe using fluorescence microscopy, with a focus on the use of time-lapse imaging to analyze the(More)
In fission yeast, Mid1p, a major determinant for division plane position, defines a medial cortical compartment where it recruits myosin II at the onset of mitosis to initiate contractile ring assembly. How Mid1p is restricted to the medial cortex is unknown. We report here that in a pom1 polarity mutant, which displays a monopolar growth pattern, Mid1p(More)