The binding of calcium to the troponin complex
A) activates myosin kinase, causing phosphorylation of myosin heads.
B) disrupts cross-bridges, allowing filaments to slide past each other.
C) allows tropomyosin to bind actin.
D) opens ion channels, allowing sodium to rush into the muscle cells.
E) causes tropomyosin to shift position, exposing myosin bind sites on actin.

Question

Quizplus · Accepted Answer

Calcium binding to the troponin complex causes a conformational change in the complex, which shifts the position of tropomyosin, exposing the myosin binding sites on actin. This allows the myosin heads to bind to actin and initiate muscle contraction.

The Binding of Calcium to the Troponin Complex