The cytoskeleton is a complex three-dimensional web in the interior of eucaryotic cells. The cytoskeleton orders many structures in the cell and performs many kinds of transport and motility for the cell. It is distinguished by a high degree of spatial differentiation and anisotropy. How does the cell construct something so heterogeneous and complex?
A widely used model of protein assembly postulates that proteins are synthesized on ribosomes and released into solution within the cell, before diffusing within the cell and assembling into cytoskeletal or other structures. This model is clearly appropriate for a variety of cytoskeletal proteins, including tubulin and actin (Mitchison, 1992; Theriot and Mitchison, 1992). Because these proteins assemble after translation, much has been learned about their assembly by using in vitro protein chemistry and in vivo methods such as FRAP (fluorescence recovery after photobleaching).
However, a growing body of evidence supports a different...
