BRAINCAKEThe Role of Ca2+ and ATP in Muscle Contraction
- Calcium ions have a dual role in muscle contraction.
- They bind to troponin to move tropomyosin and expose the myosin binding sites
- They activate the ATPase activity of the myosin head
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Key terms in this lesson
- Actin
- A thin protein filament in a myofibril that, together with myosin, slides during muscle contraction.
- Myosin
- A thick protein filament in a myofibril with globular heads that bind to actin and pull it during muscle contraction.
- Tropomyosin
- A protein that winds around actin filaments and blocks the myosin-binding sites in a relaxed muscle.
- Troponin
- A globular protein complex bound to tropomyosin that binds calcium ions, causing tropomyosin to move and expose the myosin-binding sites on actin.
- ATP
- Adenosine triphosphate, the universal energy currency of cells, which releases energy for cellular reactions when hydrolysed to ADP and inorganic phosphate.