Fish muscle cytoskeletal network: its spatial organization and its degradation by an endogenous serine proteinase.

The extraction of white croaker skeletal myofibrils with KI rendered a residue in which a network of longitudinal and transverse filaments could be observed by scanning electron microscopy. A trypsin-like serine proteinase isolated from the same muscle was able to produce a complete and rapid disruption of the network, while major myofibrillar proteins were only slightly modified. This fact suggests that the disassembly of the cytoskeletal network may be an early event in the proteolysis of myofibrils. Desmin was not attacked by the proteinase under the assayed conditions, which indicates that some other unidentified component of the network would be the primary target of the action of the enzyme on myofibrils.