Abstract
Assembly in vivo has been studied both for endogenous cytoskeletal proteins and for several classes of viruses. Autoradiography of cytoskeletal proteins has shown that many associate with the cytoskeletal framework close to the time and place of synthesis. The cytoskeletal proteins rearrange after association with the cytoskeletal framework. Rearrangement in symmetrical giant cells occurs in a centrifugal and coherent pattern. Many of the cytoskeletal proteins associate cotranslationally, as shown by their puromycin resistance in a cell-free translation system. The assembly of several groups of viruses has been shown to be associated with various components of the cytoskeleton; whether such assembly is cotranslational has not yet been addressed directly.