- Microtubule organizing center
The microtubule-organizing center (MTOC) is a structure found in eukaryotic cells from which microtubules emerge. MTOCs have two main functions: the organization of eukaryotic flagella and cilia and the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division. The MTOC is a major site of microtubule nucleation and can be visualized in cells by immunohistochemical detection of γ-tubulin. In animals, the two most important types of MTOCs are the basal bodies associated with cilia and the centrosome associated with spindle formation.
Most animal cells have one MTOC during interphase, usually located near the nucleus, and generally associated closely with the Golgi apparatus. The MTOC is made up of a pair of centrioles at its center, and is surrounded by pericentriolar material (PCM) that is important for microtubule nucleation. Microtubules are anchored at the MTOC by their minus ends, while their plus ends continue to grow into the cell periphery. The polarity of the microtubules is important for cellular transport, as the motor proteins kinesin and dynein typically move preferentially in either the "plus" or "minus" direction, respectively, along a microtubule, allowing vesicles to be directed to or from the endoplasmic reticulum and Golgi apparatus.
Before cell division begins, the interphase MTOC replicates to form two distinct MTOCs (now typically referred to as centrosomes). During cell division, these centrosomes move to opposite ends of the cell and nucleate microtubules to help form the mitotic/meotic spindle. Refer to centrosome for more detailed information.
In epithelial cells, MTOCs also anchor and organize the microtubules that make up cilia. As with the centrosome, these MTOCs stabilize and give direction to the microtubules, in this case to allow unidirectional movement of the cilium itself, rather than vesicles moving along it.
Spindle pole body
In yeasts and some algae, the MTOC is embedded into the nuclear envelope as a spindle pole body. In these organisms, the nuclear envelope does not break down during mitosis and the spindle pole body serves to connect cytoplasmic with nuclear microtubules.
Plant cells lack centrioles or spindle pole bodies. Instead, the nuclear envelope itself appears to function as the main MTOC for microtubule nucleation and spindle organization during plant cell mitosis.
Structures of the cell / organelles (TH H1.00.01.2-3) Endomembrane system Cytoskeleton Endosymbionts Other internal External
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microtubule organizing center — microtubule organizing center. См. центр организации микротрубочек. (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.
Microtubule organizing center — MTOC steht für “microtubule organizing center” (etwa „Mikrotubulin organisierendes Zentrum“). In den meisten Zellen wachsen Mikrotubuli von einer begrenzten Anzahl von Startpunkten aus. MTOCs sind die Stellen in der Zelle, an denen in vivo das… … Deutsch Wikipedia
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Microtubule — Space filling model of a microtubule segment derived from cryo electron microscopy. The protofilaments are seen running along the axis of the segment. The microtubule (+) end is towards the top of the image. Microtubules are a component of the … Wikipedia
Microtubule nucleation — tubulin, gamma Identifiers Symbol TUBG1 Alt. symbols TUBG Entrez 7283 … Wikipedia
center — 1. The middle point of a body; loosely, the interior of a body. A c. of any kind, especially an anatomical c.. 2. A group of nerve cells governing a specific function. SYN: centrum [TA]. [L. centrum; G. kentron] active c … Medical dictionary
MTOC — microtubule organizing center; mitotic organizing center * * * microtubule organizing center … Medical dictionary
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центр организации микротрубочек — microtubule organizing center центр организации микротрубочек. Структура, обеспечивающая формирование и нуклеацию (перенос внутрь ядра) микротрубочек веретена деления; наиболее распространенным Ц.о.м. является центросома <centrosome>;… … Молекулярная биология и генетика. Толковый словарь.
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