Kinetochore


Kinetochore

The kinetochore (pronounced: kin et' o core) is the protein structure on chromosomes where the spindle fibers attach during division to pull the chromosomes apart.

The kinetochore forms in eukaryotes and assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis. The kinetochore contains two regions: an inner kinetochore, which is tightly associated with the centromere DNA; and an outer kinetochore, which interacts with microtubules. "Monocentric" organisms, including vertebrates, fungi, and most plants, have a single centromeric region on each chromosome which assembles one kinetochore. "Holocentric" organisms, including nematodes such as the round worm, assemble a kinetochore along the entire length of a chromosome. During mitosis, which occurs after chromosomes are duplicated during S phase, two identical "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 of the mitotic spindle. There are also motor proteins, including both dynein and kinesin, which generate forces that move chromosomes during mitosis. Other proteins 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.

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Look at other dictionaries:

  • Kinetochore — Kinétochore Image d une cellule humaine avec: microtubules en vert, chromosomes (ADN) en bleu et kinétochores en rose Le kinétochore est un assemblage supramoléculaire de protéines au niveau des régions centromériques des chromosomes mitotiques.… …   Wikipédia en Français

  • kinetochore — kinetochore. См. кинетохор. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • kinetochore — [ki net′ə kôr΄, kinēt′ə kôr΄] n. CENTROMERE …   English World dictionary

  • Kinétochore — Image d une cellule humaine avec: microtubules en vert, chromosomes (ADN) en bleu et kinétochores en rose Le kinétochore est un assemblage supramoléculaire de protéines au niveau des régions centromériques des chromosomes mitotiques. Il existe… …   Wikipédia en Français

  • kinetochore — centromera statusas T sritis augalininkystė apibrėžtis Pirminė chromosomos persmauga, prie kurios prisitvirtina achromatinės verpstės siūlai. atitikmenys: angl. centromere; kinetochore rus. кинетохор; центромера …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • kinetochore — kinetochoras statusas T sritis augalininkystė apibrėžtis Darinys, kurio išorinis sluoksnis jungiasi su mikrovamzdeliais, o vidinis – su pirmine chromosomos sąsmauka. atitikmenys: angl. kinetochore rus. кинетохор …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • kinetochore — Structure at the centromere of eukaryotic chromosomes. The kinetochore consists of inner and outer electron dense plates and a central zone containing repetitive DNA elements. Kinetochores are involved in the control of chromosome movement in… …   Glossary of Biotechnology

  • kinetochore — noun Etymology: kinet + Greek chōros place Date: 1934 1. centromere 2. a specialized structure on the centromere to which the microtubular spindle fibers attach during mitosis and meiosis …   New Collegiate Dictionary

  • kinetochore — see centromere …   Dictionary of invertebrate zoology

  • kinetochore — Multilayered structure, a pair of which develop on the mitotic chromosome, adjacent to the centromere, and to which spindle microtubules attach but not at the end normally associated with a microtubule organizing centre …   Dictionary of molecular biology


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