Fig. 2.

Tomographic reconstruction of thick filament. (A, B) Interleaved stereo images of averaged, surface-rendered frog muscle thick filament tomogram; (A) face view, (B) tilted 20°. The density threshold was selected to optimize visualization of MyBP-C (present at stripes S5–S11, corresponding to the stripe numbers in Fig. 1). Between these stripe levels are two layers of density due to crowns of myosin heads, with a periodicity of about 14.3 nm (labeled c2 and c3). (Inset) Density representation (in stereo, tilted forward 20°) of averaged tomogram of stripes 7–9, showing that MyBP-C density is weak compared to the myosin head crowns (see also Movie S3).