microtubule polymerization or depolymerization

Definition

Target type: biologicalprocess

Assembly or disassembly of microtubules by the addition or removal of tubulin heterodimers from a microtubule. [GOC:mah]

Microtubule polymerization and depolymerization are dynamic processes essential for various cellular functions, including cell division, intracellular transport, and maintaining cell shape. Microtubules are composed of α- and β-tubulin dimers that assemble into protofilaments, which then associate laterally to form hollow cylinders.

Polymerization, also known as assembly, occurs when tubulin dimers bind to the plus end of a microtubule, extending its length. This process is driven by the hydrolysis of GTP, which is bound to the β-tubulin subunit. GTP hydrolysis promotes the formation of a curved protofilament, favoring polymerization.

Depolymerization, or disassembly, occurs when tubulin dimers detach from the microtubule. This process is influenced by factors such as the concentration of free tubulin, the presence of microtubule-associated proteins (MAPs), and the GTP/GDP ratio.

Microtubule dynamics are regulated by a balance of polymerization and depolymerization, which is influenced by various factors including:

* **Concentration of free tubulin:** Higher concentrations of free tubulin promote polymerization, while lower concentrations favor depolymerization.
* **GTP/GDP ratio:** GTP bound to tubulin favors polymerization, while GDP promotes depolymerization.
* **Microtubule-associated proteins (MAPs):** Some MAPs stabilize microtubules, promoting polymerization, while others destabilize them, promoting depolymerization.
* **Drugs:** Drugs like colchicine and vinblastine inhibit polymerization, while others like taxol promote polymerization.

The dynamic nature of microtubules is essential for their function. Dynamic instability, a process where microtubules alternate between periods of growth and shrinkage, allows for rapid exploration of the cell by the microtubule cytoskeleton. This dynamic behavior is crucial for processes like cell division, where microtubules are involved in chromosome segregation.

Overall, microtubule polymerization and depolymerization are highly regulated processes that are essential for a wide range of cellular functions. Understanding these processes is crucial for understanding normal cell biology and the development of therapeutic strategies for diseases associated with microtubule dysfunction.'
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Proteins (1)

Compounds (2)