Thick filaments in skeletal muscle are made of:

**Thick filaments:** myosin II. **Each thick filament:** ~300 myosin molecules bundled. Each myosin has 2 heavy chains (with 2 heads and a coiled-coil tail) + 4 light chains. Heads form cross-bridges with actin, hydrolyze ATP, generate force. **Thin filaments:** actin (helical filament of G-actin monomers) + tropomyosin + troponin.