Attachment in some cells involve formation of focal adhesion sites for actin bundles. Retraction is not well understood. All types of intermediate filament proteins have a central alfa helical rod which is flanked by amino- and carboxy terminal domains. The alfa-helical rod is crucial in filament assembly. The variable head and tail domains seem to determine the specific functions of the different intermediate filaments.
Intermediate filaments are more stable than actin filaments or microtubules.
Intermediate filaments are thought to provide structural support to the cell. In addition, intermediate filaments are most needed to strengthen the cytoskelleton of cells of tissues of multicellular organisms, where they are subjected to mechanical stresses. Microtubules Microtubules are rigid hollow rods. Microtubules function to determine cell shape, are involved in a variety of cell movements, intracellular transport or organelles and separation of chromosomes during mitosis. Another type of tubulin is present in centrosomes, gamma-tubulin .