During prometaphase , chromosomes move back and forth. Kinesins anchor the chromosomes to the kinetochore microtubules beyond the tip where Kinesin is depolymerizing the microtubules, aided by a shortage of available tubulin dimers. A combination of motor proteins, microtubule interacting proteins and treadmilling serves to move the chromosomes. Meanwhile, dynein and dynactin — motor proteins which walk towards the - end — work on the astral microtubules, pulling the MTOCs toward the cell periphery.
During this process the nuclear envelope dissolves and so nuclear import becomes irrelevant. Cells have some mechanism for detecting the tension in the microtubules that indicates their attachment chromatids before mitosis can proceed.
Making sure that every chromatid is properly anchored is crucial for avoiding aneuploidy. By the way, other cytoskeletal elements besides microtubules also play a key role in the cell cycle. In cytokinesis , actin forms a contractile ring and, with the help of myosin II motor proteins, cinches the cell into two.
The discovery of cell cycle regulatory processes relied heavily on some neat features of popular model organisms. Saccharomyces cerevisiae budding yeast and Schizosaccharomyces pombe fission yeast can exist as haploids or diploids. This makes it possible to study the knockout phenotype at the non-permissive temperature while still having the convenience of being able to easily propagate the organisms at the permissive temperature.
The entire S. That is how many of the genes that regulate the cell cycle were discovered. Temperature-sensitive mutants at the nonpermissive temperature get stuck unable to bud and enter the S phase. C Microtubules can be cross-linked by motor proteins with different directional preferences. D When both kinesin-5 and kinesin cross-link microtubule pairs at different ratios, directional microtubule sliding or fluctuations without a preferred directed motion are observed.
A stable balance point with no relative microtubule motion cannot be achieved with motor proteins alone. Nonmotor proteins within overlapping filaments. A Nonmotor MAPs can generate frictional resistance when moving along the lattice surface. B Some proteins, such as NuMA, EB1, and Kip3, have been shown to exhibit asymmetric friction, where moving toward one end of the microtubule results in increased resistance compared with motion in the opposite direction.
C Cross-linking proteins whose microtubule binding domains possess frictional asymmetry can move directionally within fluctuating microtubule bundles. D Cross-linking proteins undergo diffusion, which can result in an entropic force that slides microtubules and opposes reduction in overlap lengths. Proposed model of spindle force map.
Sign In or Create an Account. Advanced Search. User Tools. Sign In. Skip Nav Destination Article Navigation. Review May 10 The mechanics of microtubule networks in cell division In Special Collection:. Scott Forth , Scott Forth. This Site. Google Scholar. Tarun M. Kapoor X. Correspondence to Tarun M. Kapoor: kapoor rockefeller. Author and Article Information. Scott Forth. Abbreviation used:. Received: December 12 Revision Received: March 13 Accepted: April 18 Online Issn: National Institutes of Health GM J Cell Biol 6 : — Article history Received:.
Revision Received:. Cite Icon Cite. We apologize to those whose work we were unable to cite because of space constraints. The authors declare no competing financial interests. Protein friction limits diffusive and directed movements of kinesin motors on microtubules.
Search ADS. The kinesin Klp2 organizes microtubules into parallel bundles by an ATP-dependent sorting mechanism. Adaptive braking by Ase1 prevents overlapping microtubules from sliding completely apart. The mitotic kinesin Ncd drives directional microtubule-microtubule sliding. Asymmetric friction of nonmotor MAPs can lead to their directional motion in active microtubule networks.
Measuring collective transport by defined numbers of processive and nonprocessive kinesin motors. Flexural rigidity of microtubules and actin filaments measured from thermal fluctuations in shape. The distribution of active force generators controls mitotic spindle position. Kinetochores capture astral microtubules during chromosome attachment to the mitotic spindle: Direct visualization in live newt lung cells. Microtubule organization by the antagonistic mitotic motors kinesin-5 and kinesin Bioenergetics and kinetics of microtubule and actin filament assembly-disassembly.
Two kinesins transport cargo primarily via the action of one motor: implications for intracellular transport. Cooperative responses of multiple kinesins to variable and constant loads. The bipolar mitotic kinesin Eg5 moves on both microtubules that it crosslinks. Load-dependent release limits the processive stepping of the tetrameric Eg5 motor. Kinetochore fiber maturation in PtK1 cells and its implications for the mechanisms of chromosome congression and anaphase onset.
Spindle microtubules and their mechanical associations after micromanipulation in anaphase. The elasticity of motor-microtubule bundles and shape of the mitotic spindle.
Cell cycle-dependent changes in microtubule dynamics in living cells expressing green fluorescent protein-alpha tubulin. Structural basis for the assembly of the mitotic motor Kinesin-5 into bipolar tetramers.
Measuring pushing and braking forces generated by ensembles of kinesin-5 crosslinking two microtubules. Micromechanics of the vertebrate meiotic spindle examined by stretching along the pole-to-pole axis. Cell Motil. Cytoskeleton 23, — Lloyd, C. Actin in plants. Google Scholar. The role of F-actin in determining the division plane of carrot suspension cells. Development , — Mimori-Kiyosue, Y.
Cell Biol. Mineyuki, Y. The preprophase band of microtubules: its function as a cytokinetic apparatus in higher plants. Relationship between preprophase band organization, F-actin and the division site in Allium. Muller, S. Division plane control in plants: new players in the band. Trends Cell Biol. Murata, T.
Nakamura, M. Microtubule and katanin-dependent dynamics of microtubule nucleation complexes in the acentrosomal Arabidopsis cortical array. Nakaoka, Y. An inducible RNA interference system in Physcomitrella patens reveals a dominant role of augmin in phragmoplast microtubule generation.
Otegui, M. Cytokinesis in flowering plants: more than one way to divide a cell. Plant Biol. Palevitz, B. Actin in the preprophase band of Allium cepa. Panteris, E. A role for katanin in plant cell division: microtubule organization in dividing root cells of fra2 and lue1 Arabidopsis thaliana mutants.
Cytoskeleton Hoboken 68, — Pastuglia, M. Pietra, S. Rasmussen, C. The role of the cytoskeleton and associated proteins in determination of the plant cell division plane. Plant J. Sabelli, P. The development of endosperm in grasses. Sano, T. Smertenko, A. The Arabidopsis microtubule-associated protein AtMAP molecular analysis of its microtubule bundling activity. Plant Cell 16, — Smith, L. Divide and conquer: cytokinesis in plant cells.
Plant cell division: building walls in the right places. Spinner, L. A protein phosphatase 2A complex spatially controls plant cell division. Van Damme, D. Cortical division zone establishment in plant cells. Trends Plant Sci. Vanstraelen, M. Cell cycle-dependent targeting of a kinesin at the plasma membrane demarcates the division site in plant cells. Wasteneys, G. Remodeling the cytoskeleton for growth and form: an overview with some new views.
Wiedemeier, A. Wu, S. Myosin VIII associates with microtubule ends and together with actin plays a role in guiding plant cell division. Elife 3:e Xu, T. As the motor protein continues to jam the microtubules together, the network contracts, until it can't get any smaller.
Based on this experiment, the researchers developed a model that quantifies and describes this behavior and lends insight into not only spindle assembly but also self-organization in general. This model could provide insights into how to design materials that can self-assemble or autonomously contract, like a self-squeezing sponge.
Original written by Leah Burrows. Note: Content may be edited for style and length. Science News. The research was recently published in the journal eLife. Active contraction of microtubule networks. ScienceDaily, 28 January
0コメント