For 10 points, name this basic myofibrillar structural unit of striated muscles that contains actin and myosin.
The DAG complex links the cytoskeleton to costameres to couple this multi-protein structure with the cell membrane. CapZ localizes to a region of this structure with the help of nebulin, which also serves as a "molec- ular ruler." The poly-Ig chains and PEVK region motifs account for the differential elasticity of titin at various extensions of this structure, which may be represented on a force-length plot. At the center of this structure is a pale region named for the German word heller that contains the M-line. Intercalated discs are found at this structure's Z lines. It consists of thick and thin filaments that slide during contraction. For 10 points, name this basic myofibrillar structural unit of striated muscles that contains actin and myosin.
The DAG complex links the cytoskeleton to costameres to couple this multi-protein structure with the cell membrane.
sarcomeres [or Z line and Z disk until "extensions" is read; prompt on skeletal or cardiac muscle, myocytes, muscle cells, and cross-bridges; prompt on myofibrils, thin filaments, and thick filaments until they are read; do not accept "sacromeres"]