The cytoskeleton is a network of fibers composed of proteins contained within a cell's cytoplasm. Although the name implies the cytoskeleton is stable, it is a dynamic structure, parts of which are constantly destroyed, renewed, or newly constructed.
The cytoskeleton is divided into three main types of filaments based on their size, protein composition, and function. A fourth group, septins, is emerging as a potential cytoskeletal element.
Component | Diameter | Protein(s) | Polarity | Main Functions |
---|---|---|---|---|
Microfilaments | ~7 nm | Actin | Yes | Shape, motility, endocytosis, cytokinesis |
Intermediate Filaments | ~10 nm | Keratin, vimentin, etc. | No | Mechanical support, nuclear structure |
Microtubules | ~25 nm | α/β-tubulin | Yes | Transport, division, cilia/flagella, polarity |
Septins (optional) | ~10 nm | Septins (GTP-binding) | Suggested | Cytokinesis, polarity, scaffolding |