Question

Calcium is important in skeletal muscle contraction because it -

• A. Detaches the myosin head from the actin filament
• B. Activates the myosin ATPase by binding to it
• C. Binds to troponin to remove the masking of active sites on actin for myosin
• D. Prevents the formation of bonds between the myosin cross bridges and the actin filament

Answer 1

The correct option is C Binds to troponin to remove the masking of active sites on actin for myosin

The skeletal muscle contraction is caused by calcium ions. These calcium ions bind to the protein complex troponin in order to remove the masking of active site on actin. This results in the exposure of the active-binding sites on the actin for myosin. Once exposed, myosin binds to the actin and Pi is released from the $ATP$ molecule which is bound to myosin. Upon this, myosin comes back to a lower energy state.