Intermediate filaments make up one of three major components of the cytoskeleton. Intermediate filaments are assembled from a large family of proteins that polymerize to filaments of about 10 nm in diameter, thus intermediate to that of actin filaments and microtubules. Intermediate filaments form an extensive network in the cytosol of cells, connecting both to the nuclear membrane and to the plasma membrane, and associate with numerous proteins and other subcellular structures. They provide mechanical support and shape to cells, but also contribute to intracellular organization, cytoskeletal cross-talk, cell adhesion, and cell signaling. One subgroup of intermediate filament proteins, known as nuclear lamins, form a filamentous meshwork underlying the nuclear membrane, providing mechanical support and contributing to the organization of chromatin. However, these proteins are annotated as localized to the nuclear membrane in the Subcellular Section.
The components and structure of intermediate filaments vary between different cell types. While they extend throughout the whole cytosol, immunofluorescent staining of intermediate filaments is sometimes more concentrated in the perinuclear region. Intermediate filaments often exhibit a slightly tangled structure with strands crossing every so often. They can appear similar to microtubules, but do not overlap with the microtubule marker used in the Subcellular Section.
Read more about the proteome of intermediate filaments.