Fig. 4.

Fitting the new tropomyosin model into the cryo-EM structure. a The cryo-EM density of F-actin-tropomyosin (von der Ecken et al. 2014; EM Data bank ID-6124). b, c Rigid body fitting of the actin-tropomyosin structure defined by point A’ on the map in Fig. 3d (consisting of F-actin and a tropomyosin configuration shown in green in Fig. 3b) into the cryo-EM density of a made translucent. The tropomyosin coiled-coil is shown as a red ribbon, actin subunits are shown as b ribbons or c in space-filling format