1. Calcium (Ca²⁺) ions released from the sarcoplasmic reticulum bind to troponin and change tropomyosin's shape. This exposes the actin binding sites.
2. ATP can now bind to the myosin head. This causes it to release from the actin filament.
3. ATP is hydrolyzed into ADP + Pi, which re-cocks the myosin head into its high-energy position.
4. The myosin head binds to the exposed actin binding site.
5. The myosin head changes shape as a result of binding to the actin filament. This pulls the two filaments along one another.
6. ADP + Pi are released as a result of this shape change.
7. Calcium (Ca²⁺) ions remain present so actin binding sites are still exposed.
Parent Tip: Review the logic above to help your child master the concept of sliding filament theory worksheet.
