The protein gelsolin acts on these structures to condense the protein nebulin at their boundary-defining disks, but does not affect the largest known protein, titin.  They are surrounded by lattices of desmin filaments, and their anisotropic regions are bisected by H zones.  The sliding filament model describes the action of these structures.  This action occurs when calcium ions bind to troponin C, causing them to contra
The protein gelsolin acts on these structures to condense the protein nebulin at their boundary-defining disks, but does not affect the largest known protein, titin.  They are surrounded by lattices of desmin filaments, and their anisotropic regions are bisected by H zones.  The sliding filament model describes the action of these structures.  This action occurs when calcium ions bind to troponin C, causing them to contract and pull their terminal Z-lines together.  Action and myosin filaments in myofibrils are organized into, FTP, these functional units of striated muscle.
The protein gelsolin acts on these structures to condense the protein nebulin at their boundary-defining disks, but does not affect the largest known protein, titin.  
sarcomeres