<P> Eukaryotic cells contain three main kinds of cytoskeletal filaments : microfilaments , microtubules , and intermediate filaments . Each cytoskeletal filament type is formed by polymerization of a distinct type of protein subunit and has its own characteristic shape and intracellular distribution . Microfilaments are polymers of the protein actin and are 7 nm in diameter . Microtubules are composed of tubulin and are 25 nm in diameter . Intermediate filaments are composed of various proteins , depending on the type of cell in which they are found ; they are normally 8 - 12 nm in diameter . The cytoskeleton provides the cell with structure and shape , and by excluding macromolecules from some of the cytosol , it adds to the level of macromolecular crowding in this compartment . Cytoskeletal elements interact extensively and intimately with cellular membranes . A number of small - molecule cytoskeletal drugs have been discovered that interact with actin and microtubules . These compounds have proven useful in studying the cytoskeleton and several have clinical applications . </P>
<P> Eukaryotic cells contain three main kinds of cytoskeletal filaments : microfilaments , microtubules , and intermediate filaments . Each cytoskeletal filament type is formed by polymerization of a distinct type of protein subunit and has its own characteristic shape and intracellular distribution . Microfilaments are polymers of the protein actin and are 7 nm in diameter . Microtubules are composed of tubulin and are 25 nm in diameter . Intermediate filaments are composed of various proteins , depending on the type of cell in which they are found ; they are normally 8 - 12 nm in diameter . The cytoskeleton provides the cell with structure and shape , and by excluding macromolecules from some of the cytosol , it adds to the level of macromolecular crowding in this compartment . Cytoskeletal elements interact extensively and intimately with cellular membranes . A number of small - molecule cytoskeletal drugs have been discovered that interact with actin and microtubules . These compounds have proven useful in studying the cytoskeleton and several have clinical applications . </P>
the smallest of the cytoskeleton elements is the
the smallest of the cytoskeleton elements is the
Microfilaments
Microfilaments