Katanin

File:Katanin66.jpg

|thumb|left]]

File:Katanin55.jpg

File:Katanin44.jpg

Katanin is a protein complex that plays a crucial role in the severing of microtubules. It is named after the Japanese word "katana," which refers to a type of sword, reflecting its function in cutting microtubules. Katanin is essential for various cellular processes, including cell division, neuronal development, and cytoskeletal dynamics.

Structure

Katanin is composed of two subunits: the p60 subunit, which has ATPase activity and is responsible for severing microtubules, and the p80 subunit, which is involved in targeting the complex to specific cellular locations. The p60 subunit belongs to the AAA protein family, characterized by the presence of an ATPase domain.

Function

Katanin's primary function is to sever microtubules, which are cylindrical structures composed of tubulin proteins. This severing activity is crucial for the reorganization of the microtubule network within cells. By cutting microtubules, katanin helps in the rapid remodeling of the cytoskeleton, which is necessary for processes such as mitosis, meiosis, and cell migration.

Microtubule Severing

Katanin severs microtubules by binding to the microtubule lattice and hydrolyzing ATP, which provides the energy required for the severing process. This activity is regulated by various factors, including post-translational modifications of tubulin and interactions with other microtubule-associated proteins.

Role in Cell Division

During cell division, katanin is involved in the disassembly of the mitotic spindle, a structure composed of microtubules that segregates chromosomes into daughter cells. By severing microtubules, katanin facilitates the rapid reorganization of the spindle apparatus, ensuring accurate chromosome segregation.

Neuronal Development

In neurons, katanin plays a critical role in the formation and maintenance of neuronal processes such as axons and dendrites. The severing of microtubules by katanin is essential for the dynamic changes in the cytoskeleton that underlie neuronal growth and branching.

Regulation

The activity of katanin is tightly regulated by various mechanisms, including phosphorylation, interactions with other proteins, and the availability of ATP. These regulatory mechanisms ensure that katanin's severing activity is precisely controlled in response to cellular needs.

Clinical Significance

Mutations or dysregulation of katanin have been implicated in various diseases, including neurodegenerative disorders and cancer. Understanding the function and regulation of katanin is therefore important for developing potential therapeutic strategies for these conditions.

See Also

• Microtubule
• Cytoskeleton
• Cell division
• Neuronal development
• AAA protein