Figure 5. .

Myosin thick filaments and bi-polar structures. (a) Myosin molecules aggregate in such a way as to form bi-polar filaments, with a central barezone (no myosin heads) corresponding to the centre of the sarcomere. (b) The myosin filament pack in a way that forms a cylindrical filament with the rod portions of the myosin molecules forming the backbone and the myosin heads (crossbridges) arranged in a quasi-helical array on the surface, forming an approximate three-stranded helix with an axial repeat of 429 Å, arrowed in red.