Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement.
In cell biology, the spindle apparatus is the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell.
A kinesin is a protein belonging to a class of motor proteins found in eukaryotic cells. Kinesins move along microtubule (MT) filaments and are powered by the hydrolysis of adenosine triphosphate (ATP). The active movement of kinesins supports several cellular functions including mitosis, meiosis and transport of cellular cargo, such as in axonal transport, and intraflagellar transport. Most kinesins walk towards the plus end of a microtubule, which, in most cells, entails transporting cargo such as protein and membrane components from the center of the cell towards the periphery. This form of transport is known as anterograde transport. In contrast, dyneins are motor proteins that move toward the minus end of a microtubule in retrograde transport.
The spindle checkpoint, also known as the metaphase-to-anaphase transition, the spindle assembly checkpoint (SAC), the metaphase checkpoint, or the mitotic checkpoint, is a cell cycle checkpoint during metaphase of mitosis or meiosis that prevents the separation of the duplicated chromosomes (anaphase) until each chromosome is properly attached to the spindle. To achieve proper segregation, the two kinetochores on the sister chromatids must be attached to opposite spindle poles. Only this pattern of attachment will ensure that each daughter cell receives one copy of the chromosome. The defining biochemical feature of this checkpoint is the stimulation of the anaphase-promoting complex by M-phase cyclin-CDK complexes, which in turn causes the proteolytic destruction of cyclins and proteins that hold the sister chromatids together.
A kinetochore is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. The kinetochore assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis. The term kinetochore was first used in a footnote in a 1934 Cytology book by Lester W. Sharp and commonly accepted in 1936. Sharp's footnote reads: "The convenient term kinetochore has been suggested to the author by J. A. Moore", likely referring to John Alexander Moore who had joined Columbia University as a freshman in 1932.
Timothy John Mitchison is a cell biologist and systems biologist and Hasib Sabbagh Professor of Systems Biology at Harvard Medical School in the United States. He is known for his discovery, with Marc Kirschner, of dynamic instability in microtubules, for studies of the mechanism of cell division, and for contributions to chemical biology.
Reversine, or 2-(4-morpholinoanilino)-6-cyclohexylaminopurine, is a small molecule developed by the group of Peter G. Schultz, used for stem cell dedifferentiation.
Stuart L. Schreiber is a scientist at Harvard University and co-founder of the Broad Institute. He has been active in chemical biology, especially the use of small molecules as probes of biology and medicine. Small molecules are the molecules of life most associated with dynamic information flow; these work in concert with the macromolecules that are the basis for inherited information flow.
Serine/threonine-protein kinase PLK1, also known as polo-like kinase 1 (PLK-1) or serine/threonine-protein kinase 13 (STPK13), is an enzyme that in humans is encoded by the PLK1 gene.
Kinesin-like protein KIF23 is a protein that in humans is encoded by the KIF23 gene.
Targeting protein for Xklp2 is a protein that in humans is encoded by the TPX2 gene. It is one of the many spindle assembly factors that play a key role in inducing microtubule assembly and growth during M phase.
Kinesin-like protein KIF2C is a protein that in humans is encoded by the KIF2C gene.
Kinesin-like protein KIF20A is a protein that in humans is encoded by the KIF20A gene.
Protein Regulator of cytokinesis 1 (PRC1) is a protein that in humans is encoded by the PRC1 gene and is involved in cytokinesis.
Kinesin-like protein KIFC1 is a protein that in humans is encoded by the KIFC1 gene.
Kinesin-like protein KIF2A is a protein that in humans is encoded by the KIF2A gene.
Anthony Arie Hyman is a British scientist and director at the Max Planck Institute of Molecular Cell Biology and Genetics.
Kinesin-like protein KIF11 is a molecular motor protein that is essential in mitosis. In humans it is coded for by the gene KIF11. Kinesin-like protein KIF11 is a member of the kinesin superfamily, which are nanomotors that move along microtubule tracks in the cell. Named from studies in the early days of discovery, it is also known as Kinesin-5, or as BimC, Eg5 or N-2, based on the founding members of this kinesin family.
Kinesin family member 15 is a protein that in humans is encoded by the KIF15 gene.
J. Richard McIntosh is a Distinguished Professor Emeritus in Molecular, Cellular, and Developmental Biology at the University of Colorado Boulder. McIntosh first graduated from Harvard with a BA in Physics in 1961, and again with a Ph.D. in Biophysics in 1968. He began his teaching career at Harvard but has spent most of his career at the University of Colorado Boulder. At the University of Colorado Boulder, McIntosh taught biology courses at both the undergraduate and graduate levels. Additionally, he created an undergraduate course in the biology of cancer towards the last several years of his teaching career. McIntosh's research career looks at a variety of things, including different parts of mitosis, microtubules, and motor proteins.
