Studying Cytoskeletal Dynamics in Living Cells Using Green Fluorescent Protein

The cytoskeleton is a dynamic structure comprised of at least three distinct cellular filament systems: microfilaments, intermediate filaments, and microtubules. Microfilaments are composed of assembled globular actin monomers that form a filamentous system involved in the maintenance of cell shape and polarity. Intermediate filaments are made of fibrous proteins including vimentin, cytokeratin, nuclear lamins, and neurofilament proteins that assemble into fibers providing mechanical stability to animal cells. Microtubules are formed by the assembly of tubulin (α and β subunits) producing long, rigid polymers which govern the location of membrane-bounded organelles and other cellular components. While each filament system has specific cellular functions, an emerging view of the cytoskeleton is that actin, intermediate filaments and microtubule networks function in concert to provide the cell with stability, polarity and organization.