Proteins are the workhorses of the cell, carrying out functions to keep everything running smoothly. Some proteins work on their own, but in other cases many proteins assemble together to create a complex machine. These proteins ...
Cell & Microbiology
Jan 3, 2024
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28
During cell division, chromosomes, i.e., molecules containing our genetic material, must be properly replicated and segregated so that each daughter cell receives a complete and accurate set. Now, in an article published ...
Cell & Microbiology
Jun 8, 2023
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77
Researchers led by Osaka University used cryogenic electron microscopy to analyze the atomic structure of the centromeric region of the chromosome, essential for cell division. A protein called CENP-A marks the centromere; ...
Cell & Microbiology
Feb 6, 2023
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73
The gene KINETOCHORE NULL2 (KNL2) plays a major role in the incorporation of the histone CenH3 into the centromere of chromosomes and is thus important for cell division. This same gene is also important for the production ...
Evolution
Jul 8, 2022
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50
During cell division in a mother cell, the 23 chromosomes that carry the human genome must be first copied and later delivered to two newly forming daughter cells. At least in healthy cells, the result is astonishingly flawless, ...
Molecular & Computational biology
Apr 8, 2022
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72
It's a cellular process going on since one billion years, yet we are not able to replicate it, nor to fully understand it. Mitosis, the mechanism of cell division that is so important for life, involves more that 100 proteins ...
Biotechnology
Jul 1, 2021
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10
Dr. Han Fangpu's group from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences reports the identification and functional study of the maize Knl1 gene in an article published online in PNAS. ...
Plants & Animals
May 11, 2021
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11
Starting as a single cell, organisms undergo millions of generations of divisions to ultimately generate the bones, heart, brain and other components that make up a living being. The mainspring within this intricate process ...
Cell & Microbiology
Jan 6, 2021
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395
The error-free division of mouse oocytes—the precursors of eggs—needs kinetochores that are rich in a specific microtubule crosslinker, RIKEN researchers have discovered. This finding could explain why the division of ...
Plants & Animals
Jul 31, 2020
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19
The division of cells is a highly-regulated and complex process which requires the organised collaboration of a multitude of different cellular components. Although the basic principles are known, many components and their ...
Plants & Animals
Oct 21, 2019
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3
The kinetochore ( /kɪˈnɛtəkɔər/) is the protein structure on chromatids where the spindle fibers attach during cell division to pull sister chromatids apart.
The kinetochore forms in eukaryotes, assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis.
"Monocentric" organisms, including vertebrates, fungi, and most plants, have a single centromeric region on each chromosome which assembles one kinetochore. "Holocentric" organisms, such as nematodes and some plants, assemble a kinetochore along the entire length of a chromosome.
The kinetochore contains two regions:
Kinetochores start, control and supervise the striking movements of chromosomes during cell division. During mitosis, which occurs after chromosomes are duplicated during S phase, two sister chromatids are held together each with its own kinetochore which face in opposing directions and attach to opposite poles of the mitotic spindle. Following the transition from metaphase to anaphase, the sister chromatids separate from each other, and the individual kinetochores on each chromatid drive their movement to the spindle poles that will define the two new daughter cells. Thus, the kinetochore is essential for the chromosome segregation that is classically associated with mitosis and meiosis.
Even the simplest kinetochores consist of more than 45 different proteins. Many of these proteins are conserved throughout eukaryote species, including a specialized histone H3 variant (called CENP-A or CenH3) which helps the kinetochore associate with DNA. Other proteins in the kinetochore attach it to the microtubules (MTs) of the mitotic spindle. There are also motor proteins, including both dynein and kinesin, which generate forces that move chromosomes during mitosis. Other proteins, such as MAD2 monitor the microtubule attachment as well as the tension between sister kinetochores and activate the spindle checkpoint to arrest the cell cycle when either of these is absent.
In summary, kinetochore functions include anchoring of chromosomes to MTs in the spindle, verification of anchoring, activation of the spindle checkpoint and participation in force generation to propel chromosome movement during cell division.
On the other hand, MTs are metastable polymers made of α- and β-tubulin, alternating between growing and shrinking phases, a phenomenon known as "dynamic instability". MTs are highly dynamic structures, whose behavior is integrated with kinetochore function to control chromosome movement and segregation.
This text uses material from Wikipedia, licensed under CC BY-SA
