Fig. 3: cMyBP-C forms links between the thick and thin filaments.

a, Domain map of cMyBP-C (1,270 amino acids). The C-terminal domains from C7 to C10 bind to the thick filament, the central domains C3 to C6 form the bridge, and the N-terminal domains bind to the thin filament. b, Structural model depicting the three binding regions of cMyBP-C on the tail of crown 2. c, The epitope for the binding of the C-terminal domain of cMyBP-C to the thick filament is formed by an array of crown 2 tails and places C10 and C8 in contact with crowns 3 and 1, respectively. d, Schematic representation of the bridging region of cMyBP-C. Flexibility is shown together with a plot of the angular distribution of the bridge measured in the tomographic volumes. e, Tomographic slice (0.94 nm thickness) of the C zone in the relaxed state. f, Tomogram segmentation of a 9.4-nm slab from the same region as in e, depicting the thin filament (light green), the thick filament core (blue), the myosin heads (light blue) and cMyBP-C (yellow). g, A 3D model of the sarcomere organization in the same slab as in e, showing the flexible cMyBP-C links, spanning 3–4 globular domains, linking thick and thin filaments. h, Close-up view of the connection of two consecutive cMyBP-C proteins to the same thin filament. Scale bars, 20 nm.