Intermediate filaments

Intermediate filaments are a type of cytoskeletal component found in the cells of many animal species. They are composed of a family of related proteins sharing common structural and sequence features. Originally designated 'intermediate' because their average diameter (10 nanometers) is between those of narrower microfilaments (7 nm) and wider microtubules (25 nm), they are now known to be the most stable and least soluble components of the cytoskeleton.

Structure

Intermediate filaments are made up of a series of proteins, including vimentin, desmin, lamin, and others. These proteins are all structured similarly, with a central alpha-helical rod domain and variable non-alpha-helical end domains. The rod domain is crucial for the assembly of the filaments, as it allows for the formation of coiled-coil dimers, which then pair to form staggered tetramers. These tetramers can then align and pack together to form the filament.

Function

The primary function of intermediate filaments is to provide mechanical support for the cell. They form a network that helps maintain the shape of the cell and anchor the nucleus and other organelles in place. In addition, they are involved in cell-cell and cell-matrix interactions, and play a role in signal transduction.

Intermediate filaments are also involved in a number of cellular processes, including cell movement and division. They are crucial for the integrity of the cell membrane, and disruptions in their structure or function can lead to a variety of diseases, including progeria, muscular dystrophy, and certain types of cancer.

Clinical significance

Mutations in intermediate filament proteins have been associated with a wide range of human diseases. For example, mutations in the gene encoding the intermediate filament protein keratin can lead to skin disorders such as epidermolysis bullosa simplex. Mutations in the gene encoding the intermediate filament protein neurofilament can lead to neurodegenerative diseases such as Charcot-Marie-Tooth disease.

See also

• Cytoskeleton
• Microfilament
• Microtubule
• Cell biology