Intermediate filaments lies between thin (actin, 7 nm) and thick (myosin,15 nm) microfilaments & Perform anchoring and structural functions.

Intermediate filaments are a type of cytoskeletal component found in the cells of vertebrates, and some invertebrates. They are named 'intermediate' because their diameter, typically around 10 nanometers, is between that of the smaller microfilaments (around 7 nanometers, primarily composed of actin) and the larger microtubules (around 25 nanometers, primarily composed of tubulin).

The primary function of intermediate filaments is to provide mechanical support to cells and tissues. They form a flexible network that helps maintain cell shape and integrity. They also anchor the nucleus and other organelles in place within the cell.

Here are the steps of how intermediate filaments work:

1. Polymerization: Individual intermediate filament proteins are synthesized and then polymerize to form a filament. This process involves the formation of coiled-coil dimers, which then pair up to form staggered tetramers. These tetramers align parallel to each other to form a protofilament, with eight protofilaments eventually twisting together to form a mature intermediate filament.

2. Network Formation: Once formed, the intermediate filaments create a network throughout the cell. They extend from the nuclear envelope to the cell membrane, providing a supportive framework.

3. Anchoring: Intermediate filaments are anchored to the cell membrane at cell junctions, known as desmosomes and hemidesmosomes. This anchoring helps maintain the structural integrity of tissues, as forces applied to one cell can be distributed to neighboring cells.

4. Structural Support: By providing a supportive network, intermediate filaments help resist mechanical stress, preventing the cell from being deformed. This is particularly important in cells that are subject to mechanical stress, such as muscle cells or epithelial cells in the skin.

5. Other Functions: In addition to providing structural support, intermediate filaments are involved in other cellular functions, such as cell signaling, apoptosis (programmed cell death), and wound healing.