Tsütoskelett

Tsütoskelett, or cytoskeleton, is a dynamic network of protein filaments that provides cellular shape, mechanical support, and organizational scaffolding for intracellular transport and signaling. In most eukaryotic cells it comprises three main filament systems: actin microfilaments, intermediate filaments, and microtubules. These polymers continuously assemble and disassemble, allowing rapid remodeling in response to cellular needs.

Actin filaments support the cortex, generate forces for cell movement, and form the contractile ring during cytokinesis. Microtubules form rigid tracks for vesicle transport and organize the intracellular space, form the mitotic spindle during cell division. Intermediate filaments provide tensile strength and mechanical resilience under stress. Motor proteins, including myosin (actin-based), kinesin and dynein (microtubule-based), convert chemical energy into movement along these filaments, powering transport and motility.

Regulation is achieved by a broad collection of actin- and microtubule-binding proteins that promote nucleation, branching, crosslinking, and disassembly. In animal cells, microtubules are organized by centrosomes; actin networks are regulated by Arp2/3, formins, and other factors. The cytoskeleton interacts with the plasma membrane, organelles, and endomembrane system to shape the cell and position organelles.

Functions across life include shaping plant cells, enabling neuronal transport, supporting muscle contraction, and driving cell division. Dysfunction of cytoskeletal components is linked to diseases such as cancer metastasis, neurodegenerative disorders, and muscular dystrophies. It is studied with fluorescence microscopy, cryo-electron microscopy, and molecular genetics in model organisms and cultured cells.