Fig. 7.

Schematic diagram of the molecular overlaps of one-third of the myosin molecules in the M-region illustrating the positions of the various M-region features relative to myosin rod molecular ends. The rods are taken to be about 1600 Å long, and the heads in relaxed muscle are tilted back slightly to give an apparent M-region length (centres of mass from P1 to P1′) of 1540 Å. The other two-thirds of the M-region myosins would be related to this scheme (which only shows the rod axial positions, not the lateral packing) by the 3-fold rotation of D32.