Astral microtubules

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Astral microtubules are a subpopulation of microtubules, which only exist during and immediately before mitosis. They emanate from centrosomes, but are not associated with kinetochores. They are organized into radial arrays around the centrosomes. The turn-over rate of this population of microtubules is higher than any other population.

Astral microtubules are not required for the progression of mitosis, but they are required to ensure the fidelity of the process. The functions of astral microtubules can be generally considered as determination of cell geometry. It is absolutely required for correct positioning and orientation of mitotic spindle apparatus. It is also involved in determination of cell division site based on the geometry and polarity of the cells.

The maintenance of astral microtubules is dependent on the integrity of centrosome. It is also dependent on several microtubule-associated proteins such as EB1 and Adenomatous Polyposis Coli (APC).