The key elements of cross-bridge cycling are:
1. Actin and myosin interaction: The cross-bridge cycle involves the interaction between actin and myosin filaments in muscle cells. Myosin heads attach to actin filaments to form cross-bridges.
2. ATP hydrolysis: ATP is required for the cross-bridge cycle to occur. ATP is hydrolyzed by myosin, leading to the release of energy that is used for movement of the myosin heads.
3. Conformational changes: The hydrolysis of ATP causes a conformational change in the myosin heads, allowing them to bind to actin and form strong cross-bridges.
4. Power stroke: The myosin heads undergo a power stroke, where they pivot and pull the actin filaments towards the center of the sarcomere, resulting in muscle contraction.
5. ADP and inorganic phosphate release: After the power stroke, ADP and inorganic phosphate are released from the myosin heads, but they remain bound to actin.
6. Detachment and re-energization: ATP binds to the myosin heads, causing them to detach from actin. The myosin heads then re-energize by hydrolyzing ATP again.
7. New cross-bridge formation: The re-energized myosin heads attach to a new binding site on actin, forming a new cross-bridge and continuing the cycle.
8. Ca2+ regulation: The availability of Ca2+ ions plays a crucial role in regulating the cross-bridge cycle. Ca2+ binds to troponin, allowing myosin to interact with actin and initiate the cycle.
What're the key elements of cross-bridge cycling?
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