What is the role of tropomyosin in a sarcomere?
A)It is the main protein component of thin myofilaments.
B)It blocks the active sites on actin filaments in relaxed muscle fibers.
C)It is the main component of elastic filaments.
D)It is the main protein component in thick myofilaments.
E)It binds to calcium to initiate muscle contraction.

Question

Quizplus · Accepted Answer

Tropomyosin is a protein that winds along the thin actin filaments in a sarcomere. In relaxed muscle fibers, it blocks the binding sites on actin that myosin needs to attach and initiate contraction. When calcium ions bind to troponin, it causes a conformational change that moves tropomyosin out of the way, allowing myosin to bind to actin and initiate muscle contraction.

What Is the Role of Tropomyosin in a Sarcomere