How does tropomyosin control muscle contraction?
A) It provides a bridge between actin and myosin.
B) It provides a site where ATP can be utilized.
C) Changes in its conformation expose actin-myosin binding sites.
D) It transmits an electric charge to the filaments.
E) Changes in its shape open membrane channels.

Question

Quizplus · Accepted Answer

Tropomyosin blocks the actin-myosin binding sites on the actin filaments, preventing myosin from binding and initiating contraction. When calcium ions are released into the cytoplasm, they bind to troponin, causing a conformational change that exposes the binding sites and allows myosin to bind to actin and initiate muscle contraction. Tropomyosin does not provide a bridge between actin and myosin, provide a site where ATP is utilized, transmit electric charges or open membrane channels.

How Does Tropomyosin Control Muscle Contraction