{{In eukaryotes, the cytoskeletal matrix is a dynamic structure composed of three main proteins , which are capable of rapid assembly or disassembly dependent on the cell's requirements.[1]
In all cells of all domains of life (archaea, bacteria, eukaryotes) a cytoskeleton can be found (notably in all eukaryotic cells, which include human, animal, fungal and plant cells)with the cell structure. The cytoskeletal systems of different organisms are composed of similar proteins. However, the structure, function and behaviour of the cytoskeleton may differ, depending on the organism and cell type.[2][3] Similarly, within the same cell type the structure, dynamic behaviour, and function of the cytoskeleton can change through association with other proteins and the previous history of the network.[4] ></ref>.
The cytoskeleton of eukaryotes (including human and all animal cells) has three major components. The best-known components, present also in prokaryotic cells, are microfilaments (made of the protein actin) and microtubules (made of the protein tubulin) .[3][5] By contrast intermediate filaments, which have more than 60 different building block proteins, have been found so far only in animal cells (apart from one non-eukaryotic bacterial intermediate filament crescentin).[6] The complexity of the eukaryotic cytoskeleton emerges from the interaction with hundreds of associated proteins, like molecular motors, crosslinkers, capping proteins and nucleation promoting factors.[3][4][5]
The cytoskeleton is very important for cell adhesion, growth, migration and differentation<M. Tartibi, Y.X. Liu, G.-Y. Liu, K. Komvopoulos, Single-cell mechanics – An experimental–computational method for quantifying the membrane–cytoskeleton elasticity of cells, Acta Biomaterialia, Volume 27, November 2015, Pages 224-235, ISSN 1742-7061, http://dx.doi.org/10.1016/j.actbio.2015.08.028. (http://www.sciencedirect.com/science/article/pii/S1742706115300726)
Primarily, it gives the cell shape and mechanical resistance to deformation,[2] so that through association with extracellular connective tissue and other cells it stabilizes entire tissues.[2][6] The cytoskeleton can also actively contract, thereby deforming the cell and the cell's environment and allowing cells to migrate.[4] Moreover, it is involved in many cell signaling pathways, in the uptake of extracellular material (endocytosis),[7] segregates chromosomes during cellular division,[2] is involved in cytokinesis (the division of a mother cell into two daughter cells),[3] provides a scaffold to organize the contents of the cell in space [4] and for intracellular transport (for example, the movement of vesicles and organelles within the cell);[2] and can be a template for the construction of a cell wall.[2] Furthermore, it forms specialized structures, such as flagella, cilia, lamellipodia and podosomes.
A large-scale example of an action performed by the cytoskeleton is muscle contraction. During contraction of a muscle, within each muscle cell, myosin molecular motors collectively exert forces on parallel actin filaments. This action contracts the muscle cell, and through the synchronous process in many muscle cells, the entire muscle. }}