Question

tropomyosin shifts off of the myosin - binding sites of the actin protein during the ____________ phase. multiple choice excitation coupling relaxation contraction

Explanation:

During muscle contraction, calcium ions bind to troponin, causing a conformational change that shifts tropomyosin off of the myosin - binding sites on actin, allowing myosin heads to bind and form cross - bridges for muscle contraction.

Answer:

D. contraction