Figure 3.

Schematic structure of muscle sarcomere and how FLN connects F-actin in the Z-disc. (A) Sarcomere units in striated muscle. The width of the Z-disc: fast fibers, ~30–50 nm; slow and cardiac fibers, ~100 nm. (B–E) A model of how FLNC (black) cross-links F-actin (red) in the Z-disc. Actin filaments are oriented with their plus ends in the Z-discs and their minus ends toward the center of the sarcomere. Because FLNC also interacts with transmembrane proteins such as integrins and sarcoglycans [58] (Table 1), such connections could also determine topology of FLNC and its binding proteins in the Z-disc. However, since FLNC is highly dynamic in the Z-disc, it is likely that such structure is constantly remodeled which may play a role in the fast repair of myofibrillar microdamage [59].