A three-dimensional network of fibers, composed of filamentous protein,
which runs throughout the matrix of living cells,
providing a framework for organelles,
anchoring the cell membrane, and providing a
suitable surface for chemical reactions to take place. The cytoskeleton
also provides the cell with motility – the ability of the entire cell
to move around and for material to be moved within the cell.
Three main protein systems constitute the cytoskeleton. These are, in order
of typical abundance:
Although the term "cytoskeleton" is well used and accepted, it unfortunately
gives an impression of a rather static entity. In fact, however, all three
constituents are dynamic structures: they constantly change shape through
cycles of polymerization / depolymerization and interactions with other
proteins. Each type of fiber looks and functions differently.